Heat oven to 350F then line a baking sheet with parchment paper. In a large mixing bowl, combine almond flour, coconut flour, psyllium husk fiber, baking powder, and baking soda. Whisk in poppy seeds until well combined.

Cut butter into the dry ingredients with a fork, pastry cutter, or your hands until a dough forms.

In a separate bowl, whisk together the eggs and sweetener until frothy.

Zest lemon onto a plate, add the sprinkling erythritol. Using a fork, mash the sugar and zest together and set aside to dry.

Cut the lemon in half and squeeze the juice into the egg mixture, being careful not to get any seeds in the mix, but the pulp is ok and good for texture.

Pour the egg mixture into the dough and mix well.

Place the wet dough onto the prepared parchment in a dome shape.

Gently score the wet dough in 8 triangles with a knife and bake for 20 minutes.

Remove from oven, cut into 8 triangles and separate each slice. Sprinkle with lemon sugar and bake for 10 more minutes.