Preheat oven to 375F.
6 TBSP butter (85 grams), cut in cubes & softened
8 oz dark or bittersweet chocolate (~ 1 1/2 cups)
4 oz white chocolate (~3/4 cup)
Melt the chocolate and butter over a double boiler, or in the microwave checking at 30 second intervals - be careful not to burn it. Set aside to cool.
1 1/4 cups Guinness
1 cup flour
3/4 cup cocoa
1/4 TSP salt
1 cup sugar
1 TSP vanilla
1/2 cup chocolate chips
Bake for 25 minutes, or until a toothpick comes out clean (there may be moist crumbs).
Allow to cool completely, then cut into squares . Garnish with icing sugar, if desired.