Cream sugar and butter together; add eggs and mix.
Blend flour, salt and baking powder together and add to mixture
Mix soda with milk and vanilla; mix all together.
Add apple slices and pour batter into a buttered baking dish.
In a separate bowl, combine brown sugar, flour, cinnamon and butter, mixing until crumb texture; sprinkle over apple batter.
Bake at 375 degrees for 35 to 40 minutes.