Preheat oven to 350° F.

Line a 9 x 13" pan with parchment paper. Spray the parchment with non-stick spray, set aside.

In a medium mixing bowl, using a large fine mesh strainer, sift together the flour and baking powder. Set aside.

In a large mixing bowl, cream together the butter and brown sugar.

Mix in the vanilla and peanut butter until just combined.

Add the eggs, mix until creamy.

Add in the dry ingredients, mix until well incorporated.

Using a wooden spoon, fold in the chocolate chips and M&Ms.

Scoop the batter into the pan. Using a silicone spatula to press the sticky batter into the pan evenly.

Bake for 25-30 minutes, until golden brown and a toothpick comes out clean.

Cool completely before cutting and serving.

Store in an airtight container for up to 3 days.