In a large bowl, combine diced apples with lemon juice, sugars, cinnamon and flour. Pour into a 2qt baking dish.
In a separate bowl, combine crumble ingredients. Use hands to combine butter until crumbly (this takes a few minutes). Sprinkle over top of apple mixtures. Press lightly.
Bake in a 375°F oven for 45-50 minutes, until bubbly and caramelized. Enjoy warm with a scoop of ice cream!