In a medium bowl, whisk flour, cocoa, baking soda and salt together. Set aside.

In a stand mixer fitted with the paddle attachment or in a large bowl using a hand mixer, beat the butter and sugar together on high speed until smooth and creamy, about 2 minutes.

Add in the egg, then beat until fully incorporated. Then add in the vanilla extract.

Add the dry ingredients to the wet and mix on low speed until combined.

Roll the dough into a 1-inch ball.

Roll the ball in the white sugar and place on parchment paper lined cookie sheet, 1.5 inches apart.

Bake for 8-10 minutes until the edges are set and baked.

Remove from the oven and immediately press the peppermint chocolates into the top of the cookie. Let cool completely.

Store in a closed container at room temperature for up to 5 days or freeze layered between wax paper in a freezer safe container for up to 3 months.