Chango Bars ("Monkey Man" Bars)

1/2 cup butter
1/2 cup margarine
2 cups brown sugar
3 eggs
2 1/3 cups flour
1 tablespoon baking powder
1 teaspoon salt
1 cup chocolate chips
1 cup mixed nuts

Melt butter and margarine. While this is melting, cream brown sugar and eggs, then add melted butter and margarine.

Combine flour, baking powder and salt and stir into sugar mixture. Fold in chocolate chips and nuts. Pour mixture into a greased 13 x 9-inch baking pan and bake for 45 to 50 minutes at 350 degrees F.