Butterscotch Brownies

1/2 cup butter
2 cups brown sugar (packed tightly)
2 eggs
1 tsp. vanilla
2 cups flour
1/2 tsp. salt
2 tsp. baking powder
1 cup chopped nuts

Cook butter and sugar over low heat until bubbly. Cool. Add eggs, one at a time, beating thoroughly after each addition. Add vanilla, then sifted dry ingredients and nuts; mix thoroughly. Spread in shallow 10 1/2 x 15-inch pan and bake at 350 degrees for about 25 minutes. While warm, cut in squares.