Melt 1 Tbs. butter in large skillet, allow to fry until lightly browned. Add 1 cup brown sugar and 4 Tbs. milk. Let cook for 5 minutes.
In a separate bowl mix 3 slightly beaten egg yolks, 1 heaping Tbs. flour and 1 cup of milk. pour some hot mixture into the egg mixture, mixing quickly with a wire whisk. Return mixture to brown sugar mixter and cook until thick. Pour into the pie shell. Use remaining egg whites to make a meringue, if desired.