Brownies:

2/3 cup stick butter
5 ounces unsweetened baking chocolate, cut into pieces
1 -3/4 cups sugar
2 teaspoon vanilla
3 large eggs
1 cup all-purpose flour (do not use self-rising)
1 cup chopped walnuts, optional

Heat oven to 350°F. Grease bottom and sides of 9 x 9 x 2 inch square pan with shortening. Melt butter and chocolate in 1-quart saucepan over low heat, stirring constantly. Cool slightly. Beat sugar, vanilla and eggs in medium bowl on high speed for 5 minutes. Beat in chocolate mixture on low speed. Beat in flour just until blended. Stir in walnuts, if desired. Spread in pan.

Bake 40 to 45 minutes or just until brownies begin to pull away from the sides of the pan. Cool completely before spreading with Chocolate Buttercream Frosting.

Chocolate Buttercream Frosting:

3 cups powdered sugar
1/3 cup stick butter, softened
2 teaspoons vanilla
3 ounces unsweetened baking chocolate, melted and cooled
2 to 3 tablespoons milk

Mix all ingredients except milk in medium bowl. Stir in milk until smooth and spreadable.