Preheat oven to 350F. Line an 8×8 inch pan with parchment paper.
Add flour, cocoa powder, baking powder, and salt into a medium sized bowl and whisk to combine.
Melt the butter, then stir sugar into the melted butter until well combined. Add the eggs one at a time, then stir in the vanilla. (Make sure your melted butter isn’t too warm for the eggs!)
Add the dry ingredients and then mix until just combined.
Add Nutella and peanut butter to a small, microwaveable bowl and heat in the microwave until runny, about 30 seconds. Stir peanut butter and Nutella together, and then fold into brownie mix – but do not mix.
Pour batter into the pan and bake for 20-25 minutes.
After they come out of the oven – for a holiday twist – sprinkle with holiday sprinkles or sugar while still warm.