Add the flour mixture to the butter mixture and mix until flour is combined.
Stir in the M&M’s, preferably by hand. Make sure they are well distributed, but don't over mix or they might get crushed.
1 cup M&M’s
Spray a 9 x 13 inch pan with cooking spray and press the batter evenly into the pan with a spatula. The dough will be stiff and not pourable. Add a few more M&Ms on top of the batter if desired.
Bake for 20 minutes.
Cut into squares after the bars have cooled completely.