Diaz posted a photo of her pals in the kitchen, which also included makeup artist Gucci Westman, stylist Leslie Fremar, hair stylist Long Vigi.
The actress mentioned good food and good friends, culinary love, and wrote on Instagram: "What an amazingly delicious, educational, and ridiculously FUN time I had with these awesome ladies!!!"
The group made handmade pasta and pizza.
Diaz and Barrymore worked together on "Charlie's Angels" and all three vacationed together in Mexico last year. These girls know how to have fun!
Barrymore snapped a photo of Diaz with the caption: "#friendsinnapa !"
Barrymore posted a four pack of photos with the caption, "Thank you culinary institute of America ! I learned so much with my girlfriends #GT14"
Diaz posted a pic of Barrymore using a psata press: "@drewbarrymore maimg the pasta FRESH!!! #gt14 #cia #culinarylove"
"Going to culinary school in napa ! #freshpasta #learning #eating," said Barrymore. Yummy!
She added, "I learned to make to make ravioli from scratch ! With ricotta and herbs with a brown butter sage sauce ! #iheartpasta"
Witherspoon also posted a photo of herself in a chef's hat.