Preheat the oven to 350˚F. Grease a 9-inch square pan or a 6-cup casserole or soufflé dish with gluten-free nonstick spray or coconut oil.

Make the topping: Place the coconut sugar, walnuts, almonds, coconut flour, potato starch, cinnamon, and salt in the bowl of a food processor and process until the mixture resembles a fine meal with no pieces of nuts visible.

In a small, heavy-bottomed pot, melt the coconut oil. Whisk in the stevia, vanilla, and water. Pour the coconut oil mixture in a ring around the dry ingredients in the processor and pulse until it all comes together. It should look like moist clumps. Set aside.

Make the filling: In a large bowl, toss the pear, apple, and cranberries together with the cinnamon and ginger. In a small bowl, mix together the coconut sugar, lemon juice, and stevia, and stir until the sugar begins to dissolve. Drizzle over the fruit and then toss again to coat evenly.

Turn the fruit mixture into the prepared casserole dish and sprinkle with the topping. Press down gently on the topping. Bake for 40 to 60 minutes (depending on the depth of your pan, you will need more or less time for the fruit to cook), rotating the dish about halfway through baking, until the crumble topping is deeply browned and the fruit is soft. Serve immediately or at room temperature with a little whipped cream, if desired.