Bay seniors who have clocked a lifetime in kitchens know that the biggest challenge is baking, If you’re just a few teaspoons or degrees off, it can spell disaster. And why would you even try, for example, to recreate classic French macaroons when you can now buy them just about anywhere? Well, why not? Bonbini in the Mission offers three classes this month on these penultimate cookies. $85 a session. Other classes at Bonbini include Opera Cake, Ombre Rose Cake and Pate a choux. Delicieux!