Preheat oven to 375°F. Line a standard muffin tin with paper liners.
In a large bowl, add all dry ingredients (almond flour, coconut flour, sweetener, poppyseed, baking powder, baking soda, and salt) and stir until combined.
Add all wet ingredients into dry, and stir gently until combined.
Distribute batter evenly between all muffin cups. Bake 20-25 minutes.
Allow to cool.
Make glaze: combine butter and powdered sweetener in a bowl and stir until smooth. Add lemon juice slowly until desired consistency is reached. Spread over the top of each muffin. Sprinkle with additional lemon zest if desired.
Notes
These muffins are best enjoyed at least 6-8 hours after baking or the next day for ideal texture and depth of flavor.*For sweetener, I use Lakanto classic sweetener in the muffins, and Lakanto powdered sweetener for the glaze. You can use code SARAH for 20% off their website.