Deep chocolate with york peppermint candies and a mint buttercream filling. Yum.
I took a hint for the cookie from The Novice Chef and then made it my own. Thank you!
Here you go: great for kids of all ages…

1 cup all-purpose flour
1/3 cup unsweetened cocoa
1/2 tsp baking powder
1/4 tsp baking soda
1/4 tsp salt
5 Tbsp butter, softened
3/4 cup sugar
1 large egg
1 tsp vanilla extract
1/3 cup York mini candies (the ones that look like m&ms)

Cream wet, add dry. Bake at 350 for 9-11 minutes. Let cool completely.

1 sticks unsalted butter, softened
1.5 cups powdered sugar, sifted
2 t milk
2 t peppermint extract

Cream butter for about 5 minutes. Add in sugar and keep beating for about 5 total minutes. Add in milk and extract. Beat a little more till light and fluffy.

Then put buttercream in between 2 cookies and enjoy!