Grasshopper Brownies

Name: Grasshopper Brownies
Ingredients: 1 1/2 sticks (3/4 cup) unsalted butter; 10 1/2 oz fine-quality bittersweet chocolate (not extra-bitter or unsweetened and no more than 60% cacao if marked), finely chopped; 1 1/2 cups packed light brown sugar; 3 large eggs, lightly beaten; 1 1/4 teaspoons vanilla; 3/4 cup all-purpose flour; 1/4 cup plus 2 tablespoons unsweetened Dutch-process cocoa powder; 3/4 teaspoon salt; 1/2 cup heavy cream (see recipe notes); 10 oz fine-quality white chocolate, chopped (see recipe notes); 2 tablespoons green crème de menthe (I skipped this and found the mint flavor strong enough; compensated for the tinting with a single drop of green color); 1 teaspoon peppermint extract; 1 cup heavy cream (see recipe notes); 10 oz fine-quality bittersweet chocolate (not unsweetened), finely chopped