Preheat oven to 350° F. Line a cookie sheet with parchment paper or a silicone baking mat.
In a double boiler, or in a glass or metal bowl fitted over a pot of barely simmering water, melt the 2 cups of chocolate and butter together. Stir and remove from heat to let cool slightly.
In a small bowl combine the flour, baking soda, baking powder and salt.
In a stand mixer fitted with a paddle attachment or with a hand mixer, cream together the eggs and brown sugar for about 3 minutes. Next stir in the slightly cooled chocolate and vanilla followed by the flour mixture. Stir until you can no longer see any flour, but don’t over work the batter.
By hand, using a wooden spoon, stir in the peanut butter chips. Let the batter sit for 5-10 minutes to firm up.
Scoop the batter out using a medium sized ice cream scoop or a large spoon onto the prepared cookie sheet. Make sure to space them at least 1 ½ inches apart to account for spreading.
Bake for 11-13 minutes, or until puffed, and they look slightly shiny and cracked on top. Remove from cookie sheet and let cool fully on a cooling rack.