Preheat the oven to 350°F (175°C)
Peel, core, and slice 6 to 8 apples
Place the apple slices in a greased baking dish
Toss the apples with 1/2 cup sugar, 1 teaspoon cinnamon, and 1 tablespoon lemon juice
In a bowl, mix 1 cup oats, 1 cup flour, 1 cup brown sugar, 1/2 teaspoon salt, and 1 teaspoon cinnamon
Cut in 1/2 cup cold butter until the mixture becomes crumbly
Sprinkle the topping evenly over the apples
Bake for 35 to 45 minutes until the topping is golden and the apples are tender
Let it cool slightly before serving