Francesca Grillo, 35, who along with her sister Elisabetta, 41, is on trial accused of defrauding Ms Lawson and her former husband Charles Saatchi of £685,000, said she never saw Ms Lawson taking drugs, but did find evidence of drug use on many occasions.
She said she first saw the rolled-up notes in the kitchen of the food writer's home in Shepherd's Bush, London, after a party and also in a guest bedroom.
One of her jobs as Ms Lawson's aide was to exchange items between her handbags, and she would find rolled-up banknotes in those, she told Isleworth Crown Court, London. Asked how often she found the banknotes, Ms Grillo said: "Frequently. Every time I went through her handbag there was some notes. It was very frequent."
Asked if she ever raised the issue of drugs, she replied: "No. I didn't think it was my place."
Ms Lawson would tell Francesca, "You're good at finding things", and ask her to look for belongings in her handbags, the jury heard.She told the court Ms Lawson mislaid things "very often", adding: "Keys, her phone, her mustard."
The jury was told Ms Lawson would sometimes come downstairs with white powder on her nose and Francesca would point it out to her, but would be told by the cook it was make-up.
Asked by defence counsel Karina Arden if the substance could have been make-up, Ms Grillo replied: "Too white to be make-up."
Ms Grillo also recalled how she improvised an excuse to protect her employer when a child found a hollow book containing what the employee thought were drugs. The defendant told the court: "She (the child) said 'Look what I found in (the) book'. It was a small plastic bag with white powder. I made up something."
Both the Grillo sisters deny the charges against them. The trial continues.