The Brownies

1. Preheat oven to 325 degrees
2. Line a 12 x 17 x 1-inch baking sheet with parchment paper
3. Using a double boiler, melt together the butter and 24 ounces of the semi-sweet chocolate
4. Mix together the eggs, vanilla, and sugar in a large bowl
5. Add the warm chocolate mixture into the egg/sugar mixture and allow to cool to room temperature
6. Whisk together 1 cup of flour, baking powder, and salt, and add to the cooled chocolate mixture
7. Toss the semisweet chocolate chunks together with the remaining ⅓ cup of flour, then fold in to the chocolate mixture
8. Pour batter into the prepared baking sheet
9. Bake for 30 minutes or until a toothpick comes out clean. Allow to cool and then refrigerate until completely cool, preferably overnight

The Mint Buttercream

1. Cream the butter in electric mixer until softened then slowly add sugar until incorporated. Then add extract and mix until light and fluffy, about 2-3 minutes
2. Spread the buttercream evenly over the cooled brownie pan and freeze until solid, about 1 hour

The Glaze

1. Using a double boiler, melt the chocolate for the glaze
2. Using an offset spatula, spread the melted chocolate over the buttercream until evenly distributed
3. Let stand until chocolate has set, and is no longer glossy

The White Chocolate Drizzle

1. Using a double boiler, melt the white chocolate
2. Dip a large spoon in the melted white chocolate and drizzle it decoratively over the chocolate glaze
3. Refrigerate until set, and cut into squares