Recipe for Butterscotch Brownies  from the Betty Crocker Cookbook  (mine 
is from the 1960s)

1/2 cup soft butter or margarine

2 c. packed brown sugar

2 eggs

1 1/2 cups of Flour

2 teaspoons baking powder

1 teaspoon salt

1 teaspoon vanilla

(optional  chopped nuts  1/2 to 1 cup)

Heat oven to 350 degrees.   Melt butter(margarine) over low heat.  
Remove from heat.  Blend in sugar.  Cool.  Stir in eggs.  Measure flour 
by dip level method.  Blend flour, baking powder, and salt.  Stir in.  
Mix in the vanilla and (optional) nuts.  Spread in well greased 9 x 13 
inch pan.  Bake 25-30 minutes.  Cut into bars while warm.  Cover or wrap 
tightly.  These do dry out and get hard otherwise.