3/4 cup all-purpose flour
1/4 cup packed light brown sugar
1/2 teaspoon salt
1/2 cup, plus 2 tablespoons granulated sugar
8 tablespoons (1 stick) unsalted butter, cut into chunks
1 cup old fashioned oats (not quick cooking)
3 pounds apples
2 tablespoons lemon or lime juice
1/2 teaspoon ground cinnamon
Preheat oven to 375F. In a large bowl, mix together flour brown sugar, salt, and 2 tablespoons sugar. Using a pastry knife, cut in the butter until crumbly. Add oats and use your fingers to mix together. Place this in the freezer to chill while you work on the apples.
Peel, core, and cut the apples into 1-inch cubes. Toss in a bowl with lemon/lime juice. Add 1/2 cup sugar and the cinnamon. Stir until combined. Place in a 2-quart baking dish and top with crumb mixture. Place baking dish on a rimmed baking sheet and bake until golden and bubbling, 55-60 minutes. Serve warm with vanilla ice cream, if desired.