Cream the Buttery Mixture by combining butter, dark brown sugar, and granulated sugar in a large mixing bowl and beating until light and fluffy.

Incorporate the eggs and vanilla into the creamy mixture, mixing until fully combined and smooth.

Mix in the leavening agent by gradually adding baking powder to the batter and ensuring it's evenly distributed.

Add the flour gradually, mixing until combined and forming a slightly sticky dough.

Fold in the chocolate chips gently to integrate evenly without over-mixing.

Mix in the M&M minis, ensuring even distribution throughout the dough.

Scoop and shape the dough into ½ oz portions, flattening them slightly on a lined baking sheet.

Bake at 375°F for about 8 minutes until the edges are golden, then cool before transferring to a wire rack.