Instructions:

1. Cookies: Preheat the oven to 350°F. LIne a baking sheet with parchment paper and set aside. 
2. In the bowl of your stand mixer fitted with the paddle attachment, mix the butter and sugar together for 2 minutes.
3. Add in the egg, vanilla, food coloring, cocoa powder, baking powder, and salt. Mix for 1 minute until combined and smooth, scraping the sides of the bowl as necessary.
4. Turn the mixer to low and add in the flour. Mix until just combined.
5. Place 2- tablespoons granulated sugar in a small bowl. Form the dough into 1- inch balls, roll into the sugar, and place on your prepared baking sheet 2-inches apart. Using the back of a spoon, press an ident into the cookie. Bake for 8-10 minutes, or until set. Transfer the cookies to a wire rack to cool completely. 
6. Filling: In the bowl of your mixer, combine the butter and the powdered sugar until smooth, 1-2 minutes. Add in the melted chocolate and mix until creamy. Add in the heavy cream and mix for an additional 30 seconds, scraping the sides of the bowl as needed. 
7. Place the frosting in a piping bag or a zip-top bag with the corner cut off. Pipe a teaspoon of frosting into the indent in each cookie. Alternately, you can spread the frosting with a spoon into the indent.