Preheat the oven to 375 line a baking sheet with parchment paper or silpat liner.
In a medium size mixing bowl combine flour, baking soda, baking powder, and salt. Set aside.
In the bowl of an electric mixer, using the paddle attachment, combine butter, brown sugar and white sugar. Cream together until well incorporated.
Add in the egg and vanilla and continue mixing until well mixed.
Gradually add in dry ingredients mixing thoroughly between each addition.
After the dry ingredients are all incorporated add in the chocolate chips and M&M’s gently mix on low until they are well distributed through the dough. I like to use the dough hook for this step but you can use the paddle attachment.
Scoop the dough onto the prepared cookie sheet. To make these cookies nice and big scoop 2 Tbsp at a time. I like to use an ice cream scoop. If desired press additional M&M’s into the dough scoops to decorate the cookies.
Bake for 10-15 minutes or until golden brown around the edges. Allow to cool on the cookie sheet for 1-2 minutes and then move to a cooling rack to cool completely.
Store in an airtight container.