Apple Crumb Dessert

This is probably a classic that everyone already has their favorite recipe. We had lots of apples so I just flew by the seat of my pants and made this, it probably exists in the world wide web but I didn't follow it I just made it up...well mostly.

Filling
9 apples (I used yellow ones I think they were Jonah Gold) (peeled, cored and cut into chunks)
1 cup brown sugar
1 cup white sugar
2-3 tablespoons, lemon juice
1/4 cup flour (I actually forgot this so it was really watery, this will thicken it up)
1 TBSP-ish cinnamon

Topping
1 1/2 cup oats ground fine (I did it in my blender)
3/4 cup flour
1/2 t salt
1 1/2 cup brown sugar
1/2 cup butter

For Filling
Mix all ingredients and pour into a 9x13 pan.

For Topping
Mix all dry ingredients and cut in butter until it is fine and crumbly. Spread on top of filling.

Bake at 350 for 45 minutes. Serve warm with Vanilla ice cream!