Preheat Your Oven: Preheat your oven to 350°F (176°C) and grease a loaf pan or line it with parchment paper.
Mix Dry Ingredients: In a mixing bowl, whisk together the almond flour, coconut flour, baking powder, and salt. Add in the sweetener and mix well.
Mix Wet and Dry Ingredients: Gently add in the eggs, the butter, and the sour cream into the dry ingredients until well combined.
Make the Blueberry Puree: In a blender, combine the blueberries, and the lemon juice. Blend until smooth. Reserve 1- 2 tbsp of the blueberry puree in a separate bowl for the icing.
Add Blueberry Puree: Gently fold in the blueberry puree into the batter and mix until well combined.
Add Lemon Zest: Add the lemon zest to the mixture.
Transfer to Loaf Pan: Pour the cake batter into the prepared loaf pan, smoothing the top.
Bake: Bake in the preheated oven for approximately 50-60 minutes or until a toothpick inserted into the center comes out clean.
Cool: Remove the cake from the oven and let it cool in the pan for about 15 minutes. Then, transfer it to a wire rack to cool completely.
Prepare the Icing: In a mixing bowl combine the cream cheese, the powdered erythritol, vanilla extract and the 2 tbsp of the reserved blueberry puree. Blend well until fluffy.
Spread the icing: Spread the icing over the cooled cake.
Slice and Enjoy: Once the cake is completely cool, slice it into servings and enjoy your low-carb blueberry lemon pound cake!