In a large bowl, whisk together flour, cocoa powder, baking soda, and salt, breaking up the cocoa powder so there are no clumps.

In the bowl of a stand mixer with the paddle attached, beat the cool butter until creamy, then add sugars on medium speed for about 3 minutes, stopping to scrape the bowl often.

Add eggs one at a time, beating one low speed after each egg is added. Beat in vanilla.

Add the flour mixture and stir until fully blended, then add the peanut butter chips (or use an assortment of peanut butter and chocolate.

Using a large cookie scoop or about a quarter cup measure, scoop up big balls of dough and arrange them on a plate lined with plastic wrap. Chill the dough balls for several hours or overnight. A long chill will give you a thicker cookie.

Preheat oven to 350°F. Arrange cookies on a parchment lined baking sheet and bake for about 13-15 minutes or until fully cooked. Allow them to cool before serving. Makes 16 large cookies.