FOR BOTTOM LAYER:.
stir together oats, the 1/2 cup flour, the brown sugar, and baking soda.
Stir in the 1/2 cup melted butter.
Pat mixture into the bottom of an ungreased 11x7x1-1/2-inch baking pan. Bake in a 350 degree F. oven for 10 minutes.
FOR MIDDLE LAYER:.
Stir together egg, granulated sugar, the 2/3 cup flour, the milk, the 1/4 cup melted butter, 1 ounce melted chocolate, the 1 teaspoon vanilla, and the baking powder until smooth.
Fold in chopped walnuts.
Spread batter over baked layer in pan.
Bake about 25 minutes more or until a wooden toothpick inserted in center comes out clean.
Set on a wire rack while preparing top layer.
FOR TOP LAYER:.
In a medium saucepan heat and stir 1 ounce chocolate and the 2 tablespoons butter until melted.
Stir in the powdered sugar and the 1/2 teaspoon vanilla.
Stir in enough hot water (1 to 2 tablespoons) to make a mixture that is almost pourable.
Spread over brownies.
If desired, garnish with walnut halves.
Cool completely on wire rack. Cut into bars. Makes 32 brownies.
*Make-Ahead Tip: Prepare and bake brownies as directed. Frost and cool. Cover and store at room temperature for up to 1 day.
