Preheat oven to 350 degrees F.
Line a 13x9 baking pan with foil and spray lightly with non-stick cooking spray.
Combine cake mix, eggs and melted butter and stir until well combined. Mix in 1/2 of your M&Ms candies.
Spoon mixture into prepared pan and press lightly with fingers to fill pan with your dough. Sprinkle remaining M&Ms candies on top.
Bake for approximately 15-20 minutes, you don't want to over bake or they will dry out.
Remove from oven, allow to cool, slice and serve!