Grasshopper Brownie Bars

flour

salt

dark unsweetened cocoa powder (like Valrhona)

good quality dark chocolate (60 to 72%), coarsely chopped

butter, cut into 1 inch cubes

sugar

firmly packed light brown sugar

large eggs, at room temperature

vanilla extract

sugar

flour

milk

heavy cream

butter, softened but still cool, cut into small cubes

creme de menthe

peppermint extract

good-quality dark chocolate (60 to 72%), coarsely chopped

light corn syrup

unsalted butter, softened, cut into cubes