Preheat your oven to 350°F /180°C. Grease an 8.5 x 4.5-inch loaf pan with butter or line it with parchment paper.
In a large mixing bowl add the eggs, sweetener, vanilla extract. Using an electric mixer, mix for 2-3 minutes or until the eggs look frothy. Add the heavy cream and mix again
Combine the dry ingredients in a different bowl: the almond flour, baking powder, and coconut flour.
Combine the wet and the dry ingredients using the mixer. Add the butter and continue mixing.
Fold in the blueberries and then transfer the batter to the prepared loaf pan.
Bake for about 45-50 minutes in the preheated oven or until cooked through (it should pass the toothpick test).
Let it cool down and enjoy.
For the best results, when baking with almond flour use the super fine one. Different brands have different textures.You know it's baked when you poke it with a toothpick and comes out almost clean with a moist crumb or two but with zero uncooked batter