Preheat oven to 350 degrees F.
Mix almond flour, tapioca flour together. Sift. Add lemon zest if using. Set aside.
Separate egg whites. Save yolks for other recipes (see post end for ideas).
Make sure the white is not contaminated.
Once you have all your egg whites in mixing bowl, beat until frothy. Then add cream of tartar.
Half way through add the Swerve.
At this point, add in vanilla, almond extract, stevia glycerite.
Continue beating on high until soft peaks form. You don't want stiff peaks.
Fold in dry ingredients in three batches.
Pour batter in and smooth out.
Bake for 50 to 60 minutes until golden brown.
Once you take out of the oven, DO NOT touch the cake or it will collapse.
Immediately turn it over. You can place it over a bottle, but make sure it's even.
Wait until it's completely cool to turn back over.
Cut with fork or serrated knife.