In a large bowl or plastic zipper bag, combine granulated sugar, cornstarch, ¼ teaspoon cinnamon, and ¼ teaspoon salt. Add apples and lemon juice and toss to coat. Put in prepared baking dish.
In a large bowl combine brown sugar, flour, oats, almonds, ½ teaspoon cinnamon and ¼ teaspoon salt. Add melted butter and mix with a fork or your hands until mixture resembles crumbly wet sand. Sprinkle mixture evenly on top of apples.
Place baking dish on a rimmed baking sheet, and bake until apples are tender and topping is golden brown about 45–55 minutes. Let rest 10 minutes before serving.