Preheat the oven to 350 degrees and line a 9x9 baking dish with parchment paper
Using a standing mixer, cream together the butter, brown sugar, sugar, egg and vanilla until combined
In a large bowl, whisk together the flour, baking soda, baking powder and salt until combined
Gradually whisk in the dry ingredients into the wet until combined
Fold in the M&M’s and chocolate chips
Press the dough into the baking dish
Top a few extra pieces of M&M’s and chocolate chips on top
Bake in the oven for 20-25 minutes or until lightly brown
Remove and allow to cool completely before cutting into bars