Cream together the softened butter, sugar, and brown sugar until light and fluffy (about 2-3 minutes).

Next add the sourdough discard, egg yolk, vanilla, and peppermint extract until smooth.

To the same bowl add the flour, black cocoa powder, baking soda, and salt.

Mix until a soft dough is formed.

Cut 1 large piece of parchment paper and dust it with flour. Roll the dough out on the parchment paper as thin and even as possible—about ⅛ inch thick. Tip: Lightly flour your rolling pin to prevent sticking.

Place the rolled out dough on a large baking tray, cover it and place it into the refrigerator for 1-24 hours (The longer chill time deepens the flavor and makes the dough much easier to handle).

Once ready to bake the sourdough thin mint cookies, preheat the oven to 350 degrees F.

Remove the sheet of dough from the fridge and place it face-down on a lightly floured surface and gently peel off the parchment paper. (You can reuse that same parchment to line your baking sheet.)

Cut as many 2-inch circles as possible and transfer them to your baking sheet.

Any additional dough will need to be rolled out and cut. If the dough seems sticky add some flour or place it in the freezer to firm up.

Bake the sourdough thin mint cookies for 10-12 minutes for that crispy finish (if you’d prefer a softer cookie bake for 8-10 minutes).

Allow them to cool on the pan and cool completely before coating. They crisp up as they cool.

In a small sauce pan melt the chocolate with the coconut oil on low heat until smooth. Stir in the peppermint extract.

Fully dip each cooled cookie into the chocolate using a fork, letting the excess drip off.

Place on parchment paper and let set completely.

For that true thin mint snap, refrigerate or freeze before baking.

Store the cookies in an airtight container in the refrigerator for up to 1 week or freeze for up to 2 months. For best results, place parchment paper between layers when freezing.