Preheat the oven to 450 degrees F (230 degrees C). Lightly grease a 12-cup muffin pan with cooking spray.
Whisk together coconut flour, almond flour, whey protein, stevia powder, baking powder, and salt in a large bowl.
Combine eggs, sour cream, 1/2 cup melted butter, and vanilla extract in another bowl; mix until smooth.
Crush blueberries using a food processor.
Combine flour mixture and egg mixture until evenly mixed; add crushed blueberries and mix well.
Scoop 1/4 cup of batter into muffin cups using a small, flexible spatula, as batter will be sticky.
Bake biscuits in the preheated oven until tops are golden brown and a toothpick inserted into the middle comes out clean, 10 to 12 minutes. Let cool for 15 minutes before transferring to a serving plate.
Meanwhile, make the icing. Blend cream cheese and 1/2 cup butter together using an electric mixer until smooth and creamy, 3 to 4 minutes. Mix in stevia, cream, and vanilla extract until thoroughly combined.
