Cream together butter and sugar. Add egg and vanilla.
Alternately add the flour and baking powder with the milk.
Pour batter into a greased 9 x 13″ pan.
Spoon or pour the cherry pie filling over the batter.
Mix butter, flour and sugar together (either in food processor by pulsing or with a pastry blender or even two knives); sprinkle over pie filling.
Bake at 350º for 30-45 min. or longer if needed (knife or toothpick should come out clean).
NOTE: If top is not done, may put cake under a broiler until golden. Watch CAREFULLY as it will burn easily.