Preheat an oven to 350 Fahrenheit and spray a 9x13 baking dish with non-stick spray. *see note
Add the flour, baking powder, and mini peanut butter M&M’s together in a mixing bowl and whisk together.
In a large mixing bowl whisk the slightly cooled butter and eggs together till smooth.
Add the brown sugar, and vanilla and whisk again till smooth.
Add the peanut butter and whisk till smooth.
Add the flour mixture and M&Ms and mix with a spoon till just combined.
Turn the batter out into the prepared baking dish, smoothing the top slightly so it’s even.
Bake for 30-35 minutes or until the top is set and golden brown.
Remove from oven and let cool in baking dish till nearly completely cool before making the topping.
In the microwave in 20 second increments at 50% power, melt the chocolate chips and butter together.
Once melted, spread the chocolate on top of the bars and sprinkle with the peanut butter M&M’s