1 cup butter, softened
1 cup packed light brown sugar
1 egg, lightly beaten
1 1/3 cups all-purpose flour
1 teaspoon baking soda
2 teaspoons baking powder
1 teaspoon salt
Mix butter, light brown sugar, egg, flour and soda and bring to a rolling boil. Reduce heat to medium heat and stir in baking soda and baking powder. Cook, stirring occasionally, until mixture is thickened and well blended.
Remove from heat and stir in salt. Chill for 2 hours. Serve chilled.