Prepare Kisses: Take the frozen peppermint kisses out of the freezer and ensure they are frozen for at least 2 hours prior to baking.

Make Dough: Cream together unsalted butter and both sugars until light and fluffy. Add egg yolks and vanilla extract.

Combine Dry Ingredients: Whisk together flour, cocoa, salt, baking powder, and baking soda. Gradually mix into the butter mixture.

Chill Dough: Cover the dough and refrigerate for at least 3 hours or overnight to firm up.

Shape Cookies: Preheat oven to 350°F (175°C) and roll dough into 1-inch balls, placing them on a baking sheet.

Bake: Bake for 7-8 minutes, then press a frozen peppermint kiss into each cookie after 3 minutes of cooling.

Cool Before Freezing: Allow cookies to cool completely before packaging for storage.