Prepare your pan and oven.
Preheat the oven to 350°F / 175°C.
Grease a standard 12-well muffin pan or line it with silicone or paper liners.
Combine dry .
In a medium bowl, whisk together the almond flour, erythritol, baking powder, and salt until no lumps remain.
Combine wet .
In a separate, larger bowl, whisk the eggs until frothy.
Stir in the sour cream and vanilla extract until smooth.
Mix the batter. Gradually add the dry to the wet , stirring with a spatula until just combined. Be careful not to overmix. Gently fold in the fresh blueberries.
Fill and bake.
Divide the batter evenly among the 12 prepared muffin wells, filling each about three-quarters full.
Bake for 25 to 30 minutes, or until the tops are golden brown and a toothpick inserted into the center of a muffin comes out clean.
Cool completely.
Let the muffins cool in the pan for at least 10 minutes before transferring them to a wire rack to cool completely. This step is crucial for them to set properly. Store leftovers in an airtight container.