Preheat oven to 350 F. Grease a 9-inch pie pan or baking dish.

Make the crumble topping. In a food processor, add butter, almond flour, salt, cinnamon, vanilla and pulse until the dough comes together. Set aside.

Meanwhile, prepare the filling. Add the egg whites to a deep bowl. Using a hand-held mixer with the whisk attachment, mix on medium-high speed for 3-4 minutes until still peaks form. Add the erythritol and mix to distribute. Fold in the thawed fruit and stevia.

Pour fruit mixture into pie pan or baking dish. Drop topping over the fruit, scattering evenly.

Transfer to oven and bake 35-40 minutes, or just until topping is golden brown.