Preheat oven to 175C
Cream together butter, white sugar, and brown sugar until fluffy.
In a separate mixing bowl, sift together cocoa powder, salt, baking soda, and flour.
Add vanilla extract and eggs into butter mixture and mix well.
Mix in flour mixture into the wet ingredients until well combined.
Fold in 2 cups of peanut butter chips.
Drop heaping teaspoon balls onto lined baking sheet.
Bake for 10 mins.
Top with 3-4 peanut butter chips when cookies are hot out of the oven.
Leave to cool for 5 mins then transfer to wire racks to cool completely.
Serve with a glass of milk.