Step 1

Cream butter and both sugars with mixer until light and fluffy. Turn mixer to low and add egg yolks one at a time and mix just until incorporated. Mix in vanilla extract.

Step 2

Whisk together flour, baking cocoa, salt, baking powder and baking soda in a medium bowl. Add the dry mixture to butter mixture in 3 parts. Blend on low after each addition just until combined; scraping down the side of mixer bowl as needed. Remove bowl from mixer, cover and refrigerate for at least 3 hours up to overnight.

Step 3

Preheat oven to 350 degrees. Cover baking sheets with parchment paper or silicone mats.

Step 4

Butter hands and roll dough into a little less than 1 inch balls. Place on cookie sheet with 1-2 inches between cookies.

Step 5

Bake for 7-8 minutes. Allow to cool for 3 minutes only. Press 1 peppermint kiss into the top of each cookie. Carefully move to cookie cooling racks without touching the peppermint kiss as it may be soft.