Amish Vanilla Pie

½ cup firmly packed brown sugar
1 Tbsp. flour
¼ cup dark corn syrup
1½ tsp. vanilla
1 egg, beaten
1 cup water
1 cup flour
½ cup firmly packed brown sugar
½ tsp. cream of tartar
½ tsp. baking soda
1/8 tsp. salt
¼ cup butter
1 unbaked 9-inch pie shell

Combine first 5 ingredients in 2-quart saucepan. Slowly stir in water. Cook over medium heat until mixture come to a boil, stirring constantly. Let cool. Combine rest of ingredients (except pie shell) and mix until crumbly. Pour cooled mixture into pie shell and top with crumbs. Bake at 350° for 40 minutes or until golden brown.