1 cup butterscotch topping
1 1/4 cups white sugar
2 eggs
1 teaspoon vanilla extract
1/2 teaspoon salt
1 cup all-purpose flour
1/2 teaspoon baking soda
1 egg white
1 1/2 teaspoons buttermilk
Preheat oven to 350 degrees F (175 degrees C). Grease an 8x12 inch baking dish.
In a medium bowl, cream together butterscotch topping and 1/2 cup sugar until smooth. Beat in eggs one at a time, then stir in vanilla extract, salt and flour. Mix in baking soda and the egg white, then stir in the mixture.
Pour into prepared pan. Sprinkle top with 1/2 teaspoon baking soda.
Bake in preheated oven for 40 minutes, until a toothpick inserted comes out clean.
To make the filling: In a small bowl, beat together 1/2 cup of flour and 1/2 cup of milk, then stir in 1/2 teaspoon of baking soda. Add other milk and flour; blend just until combined.
To make the filling: In a medium bowl, cream together 1/2 cup of flour and 1/2 cup of milk until smooth. Blend in the sugar mixture. Add the vanilla and salt and blend just until combined. Add the egg white and buttermilk, blend until just blended.