Preheat your oven to 350F and line two baking sheets with parchment paper or spray with baking spray.
In a mixing bowl, whisk together the flour, baking soda, baking powder, and salt.
Using an electric mixer, beat the softened butter, granulated sugar, and brown sugar in a separate bowl until fully combined. The consistency is important here and should be slightly fluffy and cohesive. Add in the egg and pure vanilla extract, fully mixing until combined.
On low mixing speed, begin slowly adding in the flour mixture to the sugar/butter mixture until combined.
Begin stirring in the M&Ms into the batter. Only 3/4's of the total amount and put the rest on the top of the cookie scoop before baking.
Create small balls of dough, just over 1 inch in size. Place the dough balls on the baking sheets, leaving around 1 1/2 inches between each cookie for them to expand.
Bake the cookies for roughly 8-12 minutes.
Allow the cookies to cool for 5-10 minutes outside of the oven.