In a medium bowl whisk together the flour, baking soda and salt.
In the mixer or large bowl beat on medium speed the butter and sugars until fluffy approximately 3 minutes. Add the egg and vanilla and beat to combine, add the flour and beat on low, when almost combined add the m&ms and chocolate chips and combine either on low speed or by hand.
Using either a soup spoon or ice cream scoop drop spoonfuls of batter on a parchment paper lined cookie sheet. If desired add a few m&ms to the top of the dough. Refrigerate for 20-30 minutes, while the oven is pre-heating.
Pre-heat oven to 350F (180C).
Bake for 12-15 minutes or until the edges are golden. Let cool on cookie sheet for approximately 10 minutes then move to a wire rack to cool completely. Enjoy!
Keyword chocolate chip cookies, m&m cookie recipe, monster cookies