Preheat oven to 350 degrees F. Line cookie sheets (I like these ones) with parchment paper, or non stick tin foil.
In a large bowl, combine all cookie ingredients. Drop onto prepared pans using an ice cream scoop(I used this one).
Bake for 8-10 minutes. Cool on cookie sheet for 3 minutes. Remove to wire racks to cool completely.
For the Frosting
In a medium saucepan, melt butter over medium-low heat. Stir in cocoa powder.
Remove from heat. Then stir in powdered sugar a little at a time. Add heavy cream as needed to reach your desired consistency.
Notes
Ingredient Notes
Cake Mix: I'm partial to Betty Crocker's Triple Chocolate.
Eggs: Bring to room temperature to help everything incorporate smoothly.
Oil: Canola or vegetable oil will work fine.
Cocoa Powder: You can use natural or Dutch-processed cocoa powder in this recipe, as we're only using it for the frosting. I used Ghiradelli's unsweetened cocoa powder.
Tips
Line your cookie sheets with parchment paper or nonstick tin foil. This will prevent your cookies from sticking and make clean-up a breeze.
Don't Panic: Since we're leaving out the water typically called for in a cake mix, the dough will be thicker. This is normal.
Use a cookie scoop for uniform cookies that will bake at the same rate.
Frosting: Spread frosting evenly using a rubber or offset spatula. We also like to frost on a wire rack with wax paper below it to catch any drips.