Preheat the oven to 375°F and grease a 9 x 13-inch, baking dish.
To make the topping: mix the oats, flour, brown sugar and salt together in a bowl. Stir in the melted butter, maple syrup, and pumpkin and mix well. Put the topping in the freezer while you assemble the filling.
To make the fruit filling, toss the apples, cranberries, sugar, cornstarch, maple syrup and cinnamon together in a large bowl. Transfer the filling to the prepared pan and spread it out, pressing the fruit down into the corners.
Press the crumble evenly over the fruit, covering the entire mixture.
Bake for 40-45 minutes, or until the crumble is lightly golden and the filling is bubbling up in the corners.
Cool for about 20 minutes and top with ice cream or whipped cream.