When I was a baker at a conference center on Star Island, twelve miles off the coast of New Hampshire, I learned how to make this kind of cookie from one of the best bakers I know, Mandy Lamb. She would put different ingredients in the cookie each day or each week and have people try and guess what the random secret ingredients were.
Because we were on an island in New England, when storms blew in, we were trapped. No one traveled on the island, and, more important, no boats with food on them came our way, either. We had to get creative and use what we had on hand. We might not have had enough chocolate chips to make chocolate chip cookies, but if we threw in other mix-ins as well, the seven hundred some guests would never notice the shortage of one ingredient – and the cookies would always feel brand new, because they were different every time. I found that after many batches that my favorite compost cookies had my favorite snacks in them: chocolate and butterscotch chips, potato chips, pretzels, graham crackers, and coffee (grounds).
Compost cookies always turn out great in my mother’s kitchen because she infamously has a hodgepodge of mix-ins, none in great enough quantity to make an actual single-flavored cookie on its own. My brother-in-law calls them “garbage cookies”; others call them “kitchen sink cookies.” Call them what you want, and make them as we make them at Milk Bar, or add your own favorite snacks to the cookie base in place of ours.