Preheat oven to 350 degrees and a baking sheet a with parchment paper. Set aside.

Using a mixer with the paddle attachment, cream together the butter and both sugars until fluffy. Add the eggs and vanilla, and combine.

Slowly add the flour combined with the cocoa, baking soda, and salt. Mix until combined.

Remove bowl from mixer and using a wooden spoon or spatula, gently fold in the chocolate chips and Reese's Pieces.

Place drops of 1" balls onto the parchment paper {you can make them larger but then leave more room in between and adjust minutes baking}, and bake for 8-9 minutes or until centers are just set. I like to make sure they aren't cooked too much or else they won't be as soft and fluffy.