Preheat your oven to 350 degrees.
Prepare your cake mix and bake according to box instructions in a 9x13 pan.
Allow to cool for 5 minutes.
Use the bottom of a wooden spoon, a knife, or a fork to poke holes int the cake.
Combine your hot fudge, sweetened condensed milk and 1/2 tsp mint extract in a small bowl.
Pour hot fudge mixture over cake and spread over the top to completely cover the cake.
Cover cake and place it in the fridge and chill for an hour.
Fold together the cool whip, remaining mint extract and food coloring.
Spread the cool whip over the top of the cake.
Sprinkle the mint chip pieces over the top and chill for an additional 2-4 hours (or longer)
Cut and serve.