Preheat oven to 350 degrees
Combine butter, eggs, and vanilla in a large mixing bowl.
Add in flour, white sugar, brown sugar, baking soda, and salt.
Slowly fold in chocolate chips and 1 cup of M&Ms (I like to keep some for after the cookies are baked)
Using a cookie scoop or spoon, create 1” balls of dough and place them 2” apart on a baking sheet that has been lined with parchment paper.
Bake for 8-10 minutes or until the center starts to brown.
Remove from the oven and sprinkle the remaining M&Ms on top.
Let the cookies cool on the baking sheet for 5 minutes before moving to a cooling rack.