Preheat oven to 350 degrees F. Mix flour, cocoa, baking soda, and salt together. In a separate bowl, beat butter and sugar until creamy. Add eggs one at a time, beating well after each addition. Stir in vanilla. Gradually stir in flour mixture. Add peanut butter chips and stir.
Drop a tablespoon of cookie dough on cookie sheet.
Bake 8 to 9 minutes. Cookies will begin to crack on top when done.