Crumb Topping: In a medium bowl, combine the almond flour, coconut flour, sweetener, pumpkin pie spice, and salt. Stir in the butter until well combined. It will be like a thick batter. Set aside.
Pumpkin Cake: Preheat the oven to 325ºF and grease a 9×9 inch square metal baking pan. In a large bowl, whisk together the almond flour, sweetener, coconut flour, whey protein, baking powder, pumpkin pie spice, and salt. Stir in the pumpkin puree, butter, eggs, and vanilla extract until well combined. Spread the batter in the prepared pan and smooth the top. Crumble the topping mixture with your fingers into pea size pieces and sprinkle evenly overtop the cake batter. Bake 35 to 40 minutes, until the topping is golden and a tester inserted in the center comes out clean. It won’t be firm to the touch because the topping is so tender. Remove and let cool completely in the pan.
Drizzle: Whisk the sweetener, cream, and vanilla extract together until smooth. Drizzle over the cooled cake.