In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugars until light and fluffy.
Scrape down the bowl with a rubber spatula then add the eggs, beating well after each addition. Mix in the vanilla.
Sift the flour, baking powder, baking soda, and salt together then mix the dry ingredients into the butter and sugar mixture until well combined. Stir in the chocolate chunks and M&M's.
Using an ice cream scoop or a tablespoon, scoop out the dough and place on parchment lined baking sheets or cookie sheets.
Cover and place the dough in the refrigerator for at least an hour but ideally overnight.
Preheat the oven to 200°C/390°F.
Space the cookies a few centimeters apart on 2-3 cookie sheets lined with parchment paper as they will spread while baking.
Place in the preheated oven and allow to bake for 7-10 minutes until golden brown with crisp edges but still a little soft in the center.