Let's Make the Delicious Blueberry Filling First:
In a medium saucepan over medium heat, combine your blueberries, keto sweetener, and water. Bring it to a gentle boil, then reduce the heat and let it simmer for about 10 minutes, or until the blueberries are soft enough to easily mash. Give them a light mash.
Next, sprinkle the glucomannan (or xanthan gum) over the surface and whisk vigorously until it's fully combined and the mixture starts to thicken. Set this aside to cool down.
Time for the Easy Crust & Assembly:
Get your oven ready by preheating it to 350°F (175°C). Lightly grease an 8x8 inch metal baking pan.
In a large mixing bowl, whisk together the almond flour, shredded coconut, erythritol sweetener, coconut flour, and salt.
Pour in the melted butter and vanilla extract, then stir everything until the mixture starts to clump together.
Take about half of this crumbly mixture and firmly press it into the bottom of your prepared baking pan to form the base. Bake this crust for 10 minutes.
Carefully remove the pan from the oven and let the crust cool for about 10 minutes. Once cooled, spread your lovely blueberry filling evenly over the baked crust.
Crumble the remaining half of the crust mixture generously over the blueberry layer. Gently press it down a little to help it adhere.
Pop the pan back into the oven and bake for another 20-25 minutes, or until the top crust is beautifully golden brown and the filling is bubbly.