Preheat Oven: Preheat your oven to 350°F (175°C). Grease a 9x9 inch baking dish or a similar-sized dish.
Prepare the Filling: In a large bowl, combine the sliced pears, pumpkin puree, granulated sugar, brown sugar, cinnamon, nutmeg, ginger, cloves, and vanilla extract. Mix until the pears are evenly coated with the pumpkin mixture. Pour the filling mixture into the prepared baking dish and spread it evenly.
Prepare the Crumble Topping: In a separate bowl, mix together the rolled oats, flour, brown sugar, cinnamon, and salt. Pour the melted butter over the oat mixture and stir until well combined and crumbly.
Add the Topping: Sprinkle the crumble topping evenly over the filling in the baking dish.
Bake: Bake in the preheated oven for 45-50 minutes, or until the topping is golden brown and crispy, and the filling is bubbling around the edges.
Cool and Serve: Allow the crumble to cool slightly before serving. Optionally, dust with powdered sugar for garnish.