Preheat oven to 350° and line two cookie sheets with parchment paper or silicone mats.
Combine flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
Use a stand mixer, or with a hand held mixer cream the butter until light and fluffy. Add the granulated sugar and cream for 2-3 minutes. Scrape sides well and mix another 1-2 minutes. Add the egg and mix until it is well blended. Add vanilla and mix.
With mixer on low speed, add dry ingredients and mix for 1-2 minutes until well combined. Scrape sides of bowl and add white chocolate and semi sweet chocolate chips.
Using a tablespoon or a 1 oz cookie scooper, scoop cookie dough into 20 portions and place 10 cookies per sheet pan.
Bake at 350° for 10 minutes total, rotating and switching pan location in oven after 5 minutes.
Allow to cool before removing from cookie sheet.
