1 stick (1/2 cup) butter, softened
1 cup sugar
4 eggs
4 squares (1 ounce each) unsweetened chocolate, melted
1 tsp. vanilla extract
1 cup all-purpose flour
1/4 tsp. baking powder
1/4 tsp. salt
1 1/2 cups chopped walnuts
1 1-pound, 2.25-ounce pkg. yellow cake mix
1 firm stick butter, diced, optional
1 20-ounce can pineapple, undrained

Beat softened butter with sugar until light and fluffy. Beat in eggs, 1 at a time. Mix in chocolate and vanilla. Combine flour, baking powder and salt. Stir in nuts. Spread in greased 13-by-9-inch baking pan. Sprinkle cake mix evenly over chocolate. Dot with firm, diced butter, if desired. Spoon pineapple evenly on top. Bake in 350 degree oven 40 minutes. Cool completely before serving. Refrigerate leftover brownies. Yields 24 servings.