Preheat the oven to 350 degrees. Grease a shallow 4" dish. Place the granola in the blender and pulse until fine crumbs. Place the apple slices in a bowl and sprinkle with 1 tablespoon of the crumbs and the sugar. Toss with your hands to coat.
Pour the remaining crumbs into a small bowl. Add the butter and stir together with a fork, just until combined. Lightly press half the crumbs into the bottom of the prepared dish. Arrange the apple slices over them and then sprinkle with the rest of the buttery crumbs.
Bake for 25 minutes, until the apples are soft and bubbling and the top crust has browned. Let cool a few minutes before eating. Enjoy!