Preheat oven to 350° F and spray baking sheet with nonstick cooking spray or line with parchment paper.
Using an electric mixer, cream together butter, brown sugar, and sugar. Add cream cheese and beat until combined. Beat in egg yolk and vanilla.
Add flour, cocoa powder, baking soda, and salt and mix until combined. Stir in the chocolate chips.
Scoop dough out by Tablespoonful onto prepared cookie sheet. Bake at 350° F for 12-14 minutes or until cookies are just set. Let cool completely.
Meanwhile, in a small bowl, add mascarpone cheese, powdered sugar, milk and vanilla and mix until combined and smooth.
When cookies are cooled, drizzle glaze over top of cookies. Enjoy!