Cream together butter and both sugars in a stand mixer with the paddle attachment for 5 minutes.
Add in vanilla and egg. Mix until combined. Make sure to scrap the sides of the bowl throughout.
Meanwhile add flour, pudding mix and baking soda to a medium bowl. Whisk to combine.
Slowly add in the dry ingredients to the wet in two parts.
Fold in chocolate chips and M & M's.
Portion out 12 cookies and place them on a plate. Place in the fridge for at least 2 hours or overnight. Note: You must chill dough. If not the cookies will spread!
Preheat oven to 350 degrees.
Place in the oven and bake for 10-12 minutes.
Allow cookies to cool for a couple of minutes before transferring them to a wire rack to cool completely.