For the Brownie Layer

1 box of brownie mix (9×13 size) + ingredients you need to prepare brownies (eggs, oil, water)
1 cup of semi-sweet chocolate chips

For the Frosting Layer

1/2 cup unsalted butter, softened
1/2 cup shortening
1 tsp vanilla extract
1 tsp peppermint extract
5 to 5.5 cups of powdered sugar
4 Tbsp milk
3/4 cup semi-sweet chocolate, grated or coarsely chopped in the food processor
green food coloring (optional)

For the Chocolate Layer

2 cups semi-sweet chocolate chips
1 Tbsp canola or vegetable oil