01 - Preheat the oven to 375°F. Line a baking dish with parchment paper or lightly grease with butter.
02 - Wash and core the apples, leaving the bottoms intact to create a hollow well for the filling. Place the prepared apples upright in the baking dish.
03 - In a mixing bowl, combine pumpkin purée, rolled oats, flour, brown sugar, diced butter, cinnamon, nutmeg, ginger, cloves, salt, and vanilla extract. Work the mixture with a fork or your fingers until it becomes crumbly and the butter is evenly distributed.
04 - Spoon the pumpkin spice crumble mixture generously into each apple cavity, pressing down lightly. Mound any remaining crumble on top of each apple.
05 - Bake the apples in the preheated oven for 35 to 40 minutes, until the apples are tender when pierced with a fork and the crumble topping is golden brown.
06 - Remove the baked apples from the oven and let them cool for 5 minutes. Drizzle with maple syrup if desired, and serve warm topped with vanilla ice cream or whipped cream.