It's like cookie inception: a cookie...in a cookie! Two cookies in one has never been a bad idea, but this one is particularly fabulous because there are THIN MINTS involved. Come on, I know you're obsessed. They are perfectly green for St. Patrick's Day!
Preheat the oven to 350 degrees F. Line one or more baking sheets with parchment paper or a silpat.
In a large bowl or stand mixer, beat the butter and sugar together. Scrape the sides and bottom of the bowl, then beat on medium for about 2 minutes, or until light and fluffy.
Add the eggs + yolk, peppermint extract, and food coloring.
In a separate bowl, combine flour, baking powder, baking soda, cream of tartar, and salt. Add to the wet ingredients and combine until the flour is not quite incorporated.
Use a sharp knife to chop about 30 Thin Mints into quarters. Chop a few extra and set aside.
Gently stir the cookies into the dough. Don't go crazy, you want the cookie chunks to stay big.
Cover the dough and refrigerate for about an hour.
Use a 1/4 cup measuring cup to form balls of dough and shape them into a long oval shape (not a ball shape, think more egg shape). Press a couple more cookie chunks into each cookie if they are looking sparse.
Place them on the cookie sheet (the tall way) lined with parchment paper or a silicone mat. These are very large cookies, I only did 8 cookies per pan.
Bake at 350 for about 8-10 minutes, or until BARELY starting to brown on the edges. The centers should mostly be not-shiny when you take them out, but a little shine is okay.
Immediately press several chocolate chips into the top of each cookie. (You can skip this step if you want, but who says no to more chocolate?)
Let cool 5 minutes on the pan, then remove to a cooling rack.