• Preheat the oven to 375 F.
• In a mixing bowl, add softened butter, white sugar and brown sugar then mix together until a creamy mixture forms.
• Add eggs and mix together again.
• Add black cocoa powder, flour, cornstarch, baking soda and salt and mix well until a thick cookie dough forms.
• Roll cookie dough into roughly 1-inch balls and place on a greased or lined cookie sheet.
• Bake for roughly 7-8 minutes, cookies will spread slightly and appear puffy.
• Remove from oven and let rest on the cookie sheet for a few minutes before transferring them to a cooling rack.
• When cookie is cooled completely, start making the frosting.

Instructions for Frosting:

• To make the frosting, in a mixing bowl, add softened butter, powdered sugar, salt, heavy cream, milk and vanilla extract then mix until a thick frosting forms. If frosting is too thick you can thin it with a little more milk until you get the consistency you want.
• Spread about 1 1/2 teaspoons of frosting onto the bottom side of one of the cookies then sandwich it together with another cookie's bottom side.
• Repeat for all cookies, serve and enjoy!