Preheat oven to 375 degrees

Prepare a baking sheet with non-stick cooking spray or line with parchment paper

Whisk together the flour, baking powder, baking soda, and salt in a medium bowl

In bowl of stand mixer, or large bowl with hand mixer, beat together the butter and peanut butter until fluffy

Add egg to butter and peanut butter and beat until incorporated

Beat in sugars and vanilla until combined

With mixer running, add dry mixture to wet mixture in thirds until everything is fully incorporated

Stir the M&M's into the dough

Drop dough by heaping Tablespoon fulls onto prepared baking sheet

Press down on dough gently to flatten just slightly

Bake at 375 degrees for 8-10 minutes