In a large bowl, whisk together melted butter, brown sugar, and white sugar.
1/2 cup butter, 1/2 cup brown sugar, 1/4 cup white sugar
Add in egg and vanilla and continue whisking.
1 egg, 1 tbsp vanilla
Toss in the flour, baking soda, and baking powder. Switch over to a wooden spoon or spatula and fold.
1 1/2 cups, 1/4 tsp baking soda, 1/4 tsp baking powder
Add in the mini M&M's and mini chocolate chips and fold it in.
1/2 cup mini M&Ms, 1/4 cup mini chocolate chips
Line a cookie sheet with parchment paper or a silicone baking mat. Use a large cookie scoop (a 3oz cookie scoop) or your hands and scoop the dough. 9 cookies should be made in total.
Place the balls into the fridge to cool on a plate for 10-15 minutes or until they are cool to the touch.
Bake 6 cookies at a time at 350°F for 10-12 minutes. The edges of the cookies will be a light golden brown colour when removed from the oven. The inside will look soft.
Remove from the oven. Now would be the time to add on extra M&Ms and mini chocolate chips on top. Allow the cookies to sit on the tray for an additional 5 minutes before transferring to a cooling rack.
1/2 cup mini M&Ms, 1/4 cup mini chocolate chips
Enjoy!