A debate with Yotam Ottolenghi and Helen Goh on the merits of any particular cake, biscuit or pudding, spirals into serious, labyrinthine assessments of silkiness and nuttiness, crumb size and snap. (There is, they will tell you, an art to ensuring a biscuit has as much crunch when it's liberated from the oven as it does after three days in a tin).

You quickly realise they'd be utterly formidable on Bake Off.

Israeli-British chef Yotam, 48, co-owner - with Sami Tamimi - of the Ottolenghi delis and restaurants, and pastry chef and psychologist Helen, 51, have spent the last three years concocting and wrangling over sugary treats like this to include in their new book of desserts, Sweet. It's his sixth book and her first.

In it there are mini berry frangipanes, decadent cream-frosted puds and cookies galore - all of which have been put through the pair's ruthless, multi-stage recipe-testing regime. "Each recipe has to have something indefinably 'Ottolenghi' about it," says Yotam.

The perfect cake depends on the time of day

"Easy!" shouts Helen when asked to pick the bake she'd fancy a slice of right now. "The prune and Armagnac cake." (It has a rubbly walnut topping, dusted with clouds of icing sugar).

"It depends on the time of day, right?" ponders Yotam. "Now, I don't want anything creamy, I just want something that would be really nice with a cup of tea.

"But in the evening, something more dessert-y. I really love the - you know how much I like strawberries and vanilla - the rhubarb strawberry crumble cake..." We all glaze over in a sugar-spiked reverie.

"There was always going to be an Ottolenghi pastry book, the question was when," he adds, explaining how the Ottolenghi deli windows have become synonymous with sweet things, particularly the brand's huge and billowy meringues.

"Before you, no one had taken meringues seriously," Helen tells Yotam proudly.

Baking offers escape and brings back memories

The pair collided in 2006, when Helen, who hails from Melbourne, Australia via Malaysia, moved to the UK. She began by encouraging Yotam to up the patisserie and sugar-work in the deli windows, and won him over with her remarkable attention to detail and oaty Australian Anzac cookies. They've been friends and partners in pastry ever since - after all, "you don't eat a cake by yourself," says Helen with a grin.

With baking, it's the precision and escape that appeals to her: "There's a satisfaction of following the steps and then getting something at the end - just that sense of achievement, and that sense of flow. You have to be accurate and very focused, which means you forget about everything else."

For Yotam, it's the way baking intersects with memory: "We're all yearning for things that feel comforting and reminiscent of home - and I think baking really brings that across, even more than other forms of cooking."

"And we feel a bit disjointed about our reality [at the moment]," he adds thoughtfully, "with so much of it not being real, so much of it happening on computer screens and TV screens. I think baking just creates that sense of place, of home."

Demonizing sugar makes you want it more

One thing they were highly aware of throughout making Sweet, was the negative conversations being had around sugar - the mainstream demonization of the white stuff.

"The difficulty at the moment is creating a clear understanding of what you expect of sugar," says Yotam. "Whenever you demonise something, you want it even more; it creates an unhealthy relationship."

"We've always been raised eating a little bit of sugar, but somewhere along the way, that relationship has become a little bit broken," he says, explaining how a bewildering distance has opened up between us and sugar: "It's mainly to be blamed on mass-produced food, and sugar added where it doesn't need to be, so how are you meant to trust your instincts on it now?

"There is room for a piece of cake, room for a bar of chocolate - there is room for all of these things in our lives - but we need to do it consciously."

Know what you are eating and relax a little

"It's about savouring what you eat," Helen agrees.

"And if you make it [yourself], you know exactly what goes in - you are much more aware of what you're eating," adds Yotam. "I think generally we should be a little bit more relaxed about everything, and the rest will follow."

These little treats look spectacular but "can often taste more fabulous than they look".

Not this version though. After some less-satisfying experiments, Yotam Ottolenghi and Helen Goh created it at one of their weekly pastry meetings.

They explain: "There were various things lying around which came together in a flash - some empty tart shells, candied pecans, an open can of chestnut spread.

"At the same time, [we] both grabbed an empty shell, filled it with the chestnut spread, spooned over smooth whipped cream and added the element that had been missing - the candied pecans - which brought the crunch and the look needed.

"There's a metaphor in there, we're sure, about climbing mountains, and not giving up, and things tasting all the sweeter when you've had to work just that little bit harder to earn them."

Ingredients

(Makes 8)

For the pastry:

200g plain flour

120g unsalted butter, fridge-cold, cut into 1cm dice

30g caster sugar

1/4tsp salt

1/2tsp white wine vinegar

3tbsp ice-cold water

For the filling:

60g dark cooking chocolate (70% cocoa solids)

320g sweetened chestnut spread (we use Clement Faugier; whichever brand you use, just make sure that it is not the unsweetened variety)

For the candied pecans:

1tbsp maple syrup

1tbsp liquid glucose

1tbsp caster sugar

120g pecan halves

1/8tsp flaky sea salt

For the vanilla whipped cream:

300ml double cream

1tbsp icing sugar

1tsp vanilla extract

1/2tsp brandy

Method

1 For the pastry, place the flour, butter, sugar and salt in the bowl of a food

processor. Blitz a few times, until it is the consistency of fine breadcrumbs, then add the vinegar and water. Continue to work for a few seconds, then transfer to your work surface. Shape into a ball and flatten into a disc, wrap in cling film and set aside in the fridge for at least one hour (or up to three days).

2 Preheat the oven to 200°C/Gas Mark 6.

3 Allow the dough to rest at room temperature for 30 minutes (if it has been in the fridge for more than a few hours) and place on a lightly floured work surface. Roll out the dough to about 3mm thick and cut out eight circles, 14cm wide. Re-roll the dough, if necessary, to get eight circles. Transfer one circle at a time to the 8-9cm wide and 2-3cm deep fluted tins and gently press the pastry into the corners of the tart tin. You want it to fit snugly and for there to be a decent amount of pastry hanging over the edge of the tart case, as the pastry can shrink a little when baked. Place in the fridge for 30 minutes to rest.

4 Line the pastry bases with baking parchment or paper liners and fill with baking beans. Bake for 18 minutes, until the pastry is golden brown at the edges. Remove the beans and paper and cook for another eight minutes, or until the base is golden brown. Remove from the oven and set aside to cool completely in the tray. Once cool, trim the pastry and set aside until ready to fill.

5 Increase the oven temperature to 210°C/Gas Mark 6. Line a baking tray (with a lipped edge) with baking parchment and set aside.

6 To make the candied pecans, put the maple syrup, glucose and sugar into

a small saucepan and place over a low heat. Stir gently until the sugar has melted, then add the pecans and salt. Stir so the nuts are coated in syrup, then tip the nuts on to the lined baking tray. Place in the oven for about eight minutes, or until the syrup is bubbling around the nuts. Remove the tray from the oven and set aside until completely cooled. When the nuts are cooled, the glaze should be completely crisp; if not, return them to the oven for a few more minutes. Once cooled, break or roughly chop the nuts into 0.5cm pieces and set aside until ready to use.

7 Make the filling when you are ready to assemble. Place the chocolate in a heatproof bowl over a pan of simmering water, making sure the base of the bowl is not touching the water. Stir occasionally until melted, then use a pastry brush to line the inside of each case with the chocolate. Set aside for about 30 minutes, to set, then fill with enough chestnut spread so it rises about halfway up the sides of the tart cases.

8 For the vanilla whipped cream, pour the cream into the bowl of an electric mixer with the whisk attachment in place. Add the icing sugar, vanilla extract and brandy and whisk on a high speed for one minute, or until medium-soft peaks form.

9 Divide the whipped cream between the tarts, so it is slightly domed on top of the chestnut spread. Sprinkle the candied pecans generously on top. Serve.

These pretty little friands would be the icing on a very fancy afternoon tea.

Created by Yotam Ottolenghi and Helen Goh, for their new cookbook, Sweet, they say: "These look splendid when iced - destined for top ranking on any tiered cake stand - but also work un-iced, in the cookie tin, for grabbing on a whim.

"They'll lose their slightly chewy edge after the first day or so, but still taste great. Blueberries or raspberries can be used instead of the blackberries. Don't use strawberries, though - they are too watery."

Ingredients

(Makes 12)

180g unsalted butter, plus an extra 10g, melted, for brushing

60g plain flour, plus extra for dusting

200g icing sugar

120g ground almonds

1 1/2tsp ground star anise (or 3 whole star anise, blitzed in a spice grinder and passed through a fine-mesh sieve)

1/8tsp salt

150g egg whites (from 4 large eggs)

Finely grated zest of 1 small orange (1 tsp)

18 whole blackberries (about 120g), cut in half lengthways

For the icing (optional):

60g blackberries (about 8), plus an extra 24 small blackberries, to garnish

3/4tbsp water

1tsp lemon juice

165g icing sugar

Method

1 Preheat the oven to 220°C/Gas Mark 7. Brush the 12 holes of a regular

muffin tin with the melted butter and sprinkle all over with flour. Tap the tray gently to ensure an even coating of the flour, then turn upside down to remove the excess. Place in the fridge to chill while you make the batter.

2 To brown the butter, place in a small saucepan and cook over a medium heat until melted. Continue to cook until the butter is foaming, gently swirling the pan from time to time, to allow the solids to brown more evenly. You will see dark brown sediments begin to form on the sides and bottom of the pan. Continue to allow the butter to bubble away until it turns a rich golden brown and smells of toasted nuts and caramel. Remove the pan from the heat and let it stand for five minutes, to allow the burnt solids to collect at the bottom of the pan. Strain through a fine-mesh (or muslin-lined) sieve, discarding the solids. Allow the browned butter to cool slightly before using.

3 While the butter is cooling, sift the flour, icing sugar, ground almonds, star anise and salt into a bowl. Place the egg whites in a small bowl and use a whisk or fork to froth them up for a few seconds. Pour the egg whites into the sifted dry ingredients and stir until incorporated. Add the orange zest and browned butter and mix until smooth.

4 Remove the muffin tin from the fridge and fill the moulds just over two-thirds of the way up the sides. Place three halved blackberries on top, cut side down, and bake for 10 minutes. Reduce the temperature to 210°C/Gas Mark 6, turn the tray around in the oven for even cooking, and continue to cook for another eight minutes, until the edges of the friands are golden brown and the centres have a slight peak and spring back when gently prodded. Set aside to cool before removing them from their moulds.

5 If you are icing the cakes, place 60g of blackberries in a small bowl with the water and lemon juice. Use a fork to mash them together, then pass the mixture through a fine-mesh sieve to extract as much fruit juice as possible - you should get about 60ml. Sift the icing sugar into a medium bowl, pour in the blackberry juice and combine to make a light purple runny icing. It should just be thick enough to form a thin glaze on the tops of the cakes. Spoon the icing over the cakes, spreading it to the edges so it runs down the sides. Place two small blackberries on each friand, set aside for 20 or 30 minutes to set, then serve.

Who doesn't love a cup of tea and a biscuit? These ones from Yotam Ottolenghi and Helen Goh, from their new cookbook Sweet, combine the nuttiness of pecans with the gooeyness of banana.

"The secret here is to slightly under-bake the cookies, which keeps them soft and fudgy," the duo explain. "Once the unbaked dough has been rolled into balls, they can be kept in the fridge for up to two days, or frozen for up to three months. You can also bake them from frozen, you'll just need to add an extra minute of cooking time."

Also, they are best eaten within a day of being made.

Ingredients

(Makes about 24)

110g unsalted butter, at room temperature, cubed

110g caster sugar

1 large egg, lightly beaten

125g plain flour

1/2tsp baking powder

20g cocoa powder

1/2tsp ground cinnamon

1/4tsp salt

100g chocolate chips (70% cocoa solids), or 100g dark cooking chocolate, cut into 0.5cm pieces

50g mashed banana (about 1/2 small banana)

170g pecan halves, finely chopped

100g icing sugar, for dusting

Method

1 Place the butter and sugar in the bowl of an electric mixer with the paddle

attachment in place. Beat on a medium-high speed until light and fluffy, then gradually add the egg and continue to beat until incorporated. Sift the flour, baking powder, cocoa powder, cinnamon and salt into a bowl, then add to the butter and sugar. Mix on a low speed for about 15 seconds, then add the chocolate and banana. Beat until combined, then transfer to the fridge for two hours to firm up.

2 When firm, use your hands to form the dough into 3cm round balls, about 20g each - you might need to wash your hands once or twice when making them, if they get too sticky. Place the pecans in a medium bowl and drop the balls into the nuts as you form them, rolling them around so that they are completely coated and pressing the nuts in so they stick.

3 Line a baking tray with baking parchment, place the cookies on the tray - there is no need to space them apart at this stage - and transfer to the fridge for at least an hour.

4 When ready to bake, preheat the oven to 190°C/Gas Mark 5. Line two baking trays with baking parchment.

5 Place the icing sugar in a bowl and roll the cookies in the icing sugar, pressing it in as you go so it sticks well. Place on the lined baking trays, spaced 2-3cm apart, and flatten the cookies to 1cm thick.

6 Bake for 10 minutes. They will be soft to the touch when they come out of the oven, so allow them to cool on the tray for 10 minutes before gently transferring to a wire rack. These can be served warm, when they will be a little gooey in the centre, or set aside until completely cool.

Sweet by Yotam Ottolenghi and Helen Goh is published by Ebury Press, priced £27. Photography by Peden + Munk. Available now.