Milk Bar is a New York City institution helmed by chef Christina Tosi. She is the visionary creative mastermind behind Cereal Milk Ice Cream and of course the incredible Compost Cookies. These "kitchen sink" style morsels are packed with sweet and savory mix-ins including chocolate chips, coffee grounds, and even potato chips! Making them at home is easier and cheaper than a trip to the Big Apple.
To make the Graham Crust: Toss the graham crumbs, milk powder, sugar, and salt with your hands in a medium bowl to evenly distribute your dry ingredients.
Whisk the butter and heavy cream together. Add to the dry ingredients and toss again to evenly distribute. The butter will act as glue, adhering to the dry ingredients and turning the mixture into a bunch of small clusters. The mixture should hold its shape if squeezed tightly in the palm of your hand. If it is not moist enough to do so, melt an additional 14 to 25 grams (1 to 1 ½ tablespoons) butter and mix it in. Stored in an airtight container, graham crust will keep fresh for 1 week at room temperature or for 1 month in the fridge or freezer.
To make the Compost Cookies: Combine the butter, sugars, and corn syrup in the bowl of a stand mixer fitted with the paddle attachment and cream together on medium-high for 2 to 3 minutes. Scrape down the sides of the bowl, add the egg and vanilla, and beat for 7 to 8 minutes.
Reduce the speed to low and add the flour, baking powder, baking soda, and salt. Mix just until the dough comes together, no longer than 1 minute. (Do not walk away from the machine during this step, or you will risk over mixing the dough.) Scrape down the sides of the bowl with a spatula.
Still on low speed, add the chocolate chips, butterscotch chips, graham crust, oats, and coffee and mix just until incorporated, about 30 seconds. Add the potato chips and pretzels and paddle, still on low speed, until just incorporated. Be careful not to over mix or break too many of the pretzels or potato chips.
Using a 2 ¾ ounce ice cream scoop (or a ⅓ cup measure), portion out the dough onto a parchment-lined sheet pan. Pat the tops of the cookie dough domes flat. Wrap the sheet pan tightly in plastic wrap and refrigerate for at least 1 hour, or up to 1 week. Do not bake your cookies from room temperature—they will not bake properly.
Heat the oven to 375°F.
Arrange the chilled dough a minimum of 4 inches apart on parchment-lined sheet pans (no more than 6 large cookies per half sheet pan). Bake for 15 to 16 minutes. The cookies will puff, crackle, and spread. They should be very faintly browned on the edges yet still bright yellow in the center.
Cool the cookies completely on the sheet pans before transferring to a plate or an airtight container for storage. At room temp, cookies will keep fresh for 5 days; in the freezer, they will keep for 1 month.
Notes
Chocolate Chips: The original recipe includes mini chips, but I use regular full-size chips. This works just fine.
Butterscotch Chips: Same as above.
Coffee Grounds: Do NOT use instant coffee, but any brand of ground coffee will work fine otherwise. Just make sure they are not wet, brewed coffee grounds. Use it fresh from the canister.
Rolled Oats: Use rolled oats, not instant oats.
Potato Chips: Both the Milk Bar staff and I recommend Cape Cod Potato Chips. They are thicker and more crunchy than other brands, and hold up well in the cookies. The reduced fat version works fine too!
Mini Pretzels: Others who make this recipe suggest chopping the pretzels. This isn't necessary. The pretzels will break up a bit in your mixer, but you also want some large chunks and full pretzels in there. Don't over-mix!
This recipe uses kosher salt (aka cooking salt, kitchen salt, coarse salt outside of the US). If you are using table salt, definitely scale down the salt as that is a saltier type of salt! The type of salt will make a big difference in how salty your food tastes, so keep that in mind.
For portioning the cookies, I use this Oxo ice cream scoop which is a #12 size, with a 2 ½ fluid ounce capacity.
While you can certainly make smaller cookies, you will likely need to break up the pretzels and potato chips a bit more to do so. Also bake smaller cookies for less time.
To freeze: Freeze the chilled, flattened cookie dough rounds in a freezer bag. Frozen cookie dough can last about 3 months in the freezer. When ready to bake, remove as many circles of dough as you desire, and thaw them in the refrigerator (you can bake from a frozen state, but I always feel like they don't spread out as nicely). Bake as directed in the recipe. You may need an extra minute or two of baking time if the dough is partially frozen.