To a small mixing bowl, add the granola, melted butter, and flour and mix with a wooden spoon until combined. Set the crumble mixture aside while you preheat your oven to 375°F (190°C).
Meanwhile, prepare your peaches by rinsing, slicing them in half, and removing the pit. There is no need to peel the peaches for this recipe.
Once your oven is preheated, spread the crumble topping out into an even layer on a baking sheet, and bake for 10 to 15 minutes, or until golden brown.
Meanwhile, heat your outdoor grill or grill pan over medium heat. Brush the cut sides of the peaches generously with extra-virgin olive oil to cook on a grill pan, or canola or another high smoke point oil if using an outdoor grill.
Once your grill is hot, place the peaches cut side down on the grill and cook uncovered for 4-5 minutes, or until defined grill marks appear. Brush the skin side with oil, flip the peaches, and cook for another 4-5 minutes.
Transfer the peaches to a serving platter cut side up, drizzle them with maple syrup, and spoon about a tablespoon of the crumble topping onto each peach half.
Serve the peaches with a scoop of vanilla ice cream if desired. Enjoy!