Preheat your oven to 350°F so it’s ready when your dough is mixed.

In a large mixing bowl, combine the cake mix, eggs, and oil. Stir until everything is well blended and a soft dough comes together.

Fold in the red and green M&Ms, making sure they’re evenly distributed throughout the dough.

Transfer the mixture to your prepared pan. Spread it out evenly, pressing it gently into the corners and edges.

Bake for 25-28 minutes, or until the top is golden brown and the center is set.

Remove from the oven and let the cookie bars cool completely in the pan.

Once cooled, slice into squares or rectangles.

Serve and enjoy!