Preheat your oven to 350°F (175°C). Line a 12-cup muffin tin with parchment liners or silicone liners.
In a large bowl, whisk the almond flour, erythritol, baking powder, and salt together until evenly combined.
In a separate bowl, whisk the eggs, melted butter, sour cream, vanilla extract, and lemon zest until smooth. Pour into the dry ingredients and stir until just combined. Gently fold in the blueberries, being careful not to crush them.
Divide the batter evenly among the 12 muffin cups, filling each about three-quarters full.
Bake for 22 to 26 minutes, or until the tops are golden and a toothpick inserted in the center comes out clean.
Let the muffins cool in the tin for 10 minutes, then transfer to a wire rack to cool completely. Store leftovers in an airtight container in the refrigerator for up to 5 days.
