In a bowl combine all your dry ingredients; flour, baking soda & salt. Set aside
In a large bowl combine butter and all 3 sugars and cream together using an electric mixer on medium speed for a few minutes until light & fluffy. Add in egg and vanilla extract and continue mixing. Slowly add in dry ingredients and continue mixing until your cookie dough forms and everything is thoroughly combined. Fold in chocolate chips, white chocolate chips and M&Ms.
Pour cookie dough onto plastic wrap and wrap thoroughly to freeze for at least 2 to 3 hours. Take cookie dough out of freezer to thaw for about 10 to 15 minutes prior to baking.
Preheat oven to 350 and line a baking sheet with parchment paper, scoop cookie dough into small balls and place about 2 inches apart on cookie sheet. Bake for 9-10 minutes. When cookies come out of the oven place a few extra chocolate chips and M&Ms on the surfaces to make them pop.
Allow cookies to cool for about 5 minutes before serving, store any leftover in an airtight container.