Preheat oven to 375 degrees.

In bowl of a stand mixer fitted with paddle, cream together butter and both sugars until well-blended. Add eggs and vanilla and beat just until incorporated, then scrape sides of bowl and beat in cocoa powder. Scrape sides of bowl again.

In a separate bowl, thoroughly stir together flour, salt and baking powder. Stir the flour mixture into the chocolate mixture. When flour is mixed in, go ahead and fold in the chocolate chips and peanut butter chips. Divide into 10 equal portions ( you can make them larger or slightly smaller if desired).

On a parchment paper or Silpat lined or non-stick cookie sheet (don’t use grease or spray), place the cookie dough mounds.

Bake at 375 degrees for 8 minutes, then without opening oven or tampering with cookie sheet, reduce heat to 325 degrees and bake for another 8-10 minutes or until cookies appear set but still slightly moist in the center. If you have a convection oven, bake at 400 for about 8 minutes then reduce heat to 330 and bake for another 10 minutes or until the cookies have little cracks on the top.

Let cookies cool on rack for about 5 minutes, then transfer to a rack to cool and set.