Preheat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners.
In a large bowl, mix almond flour, baking powder, baking soda, salt, sugar, and lemon zest.
In another bowl, whisk together melted butter, Greek yogurt, and beaten eggs until combined.
Add wet ingredients to the dry ingredients and gently mix until just combined. Fold in blueberries carefully.
Spoon the batter into the muffin cups to fill them almost to the top. Sprinkle lightly with extra sugar and sliced almonds.
Bake for 18 minutes or until a toothpick inserted in the center comes out clean. Let muffins cool in the tin for a few minutes, then transfer to a cooling rack.
Notes
These muffins can be enjoyed warm or at room temperature. Store in an airtight container for up to 3 days.