Fill with alternating layers of apples and cinnamon-sugar mixture.
Sprinkle with lemon juice and dot with butter.
For topping, mix together flour, salt, sugar and brown sugar. Cut in butter using a pastry cutter or two knives.
Sprinkle the crumb mixture over the top and bake at 450F for 10 minutes.
Reduce oven heat to 375F and bake for another 40-50 minutes.
