In a large bowl of a mixer beat butter until smooth, add in powdered sugar and cocoa.

Pour in melted chocolate and add heavy cream and vanilla and beat on medium-high until it's all creamy and smooth.

Spread frosting onto cookies with a small offset spatula, start by applying the frosting into the center and as you press down in the center swirl the spatula around in a circle to create a pretty swirl shape of frosting on the cookies.