01 - Set the oven to 350°F (175°C) to preheat.
02 - In a large bowl, combine sliced apples, granulated sugar, ground cinnamon, lemon juice, and flour. Stir until apples are evenly coated.
03 - Transfer the apple mixture into a greased 8x8-inch baking dish, spreading evenly.
04 - In a separate bowl, blend granola, rolled oats, brown sugar, flour, ground cinnamon, and salt. Pour melted butter over and mix until crumbly and well incorporated.
05 - Evenly sprinkle the granola mixture over the apple layer in the baking dish.
06 - Bake for 40 minutes or until the topping turns golden brown and apples are tender and bubbling.
07 - Allow to cool at least 10 minutes before serving. Serve warm, optionally with vanilla ice cream or whipped cream.