Use three six-inch cake pans.
Cut parchment paper to fit each round. Spray or butter on top of parchment paper and sides.
Mix flours, salt, baking soda, baking powder, xanthan gum, together. Set aside.
Zest all lemons. Reserve some zest for topping cake later.
Rub zest into swerve with your fingers to release the lemon oil. Set aside
Beat eggs on medium high for a good five minutes until frothy.
Slowly stream in avocado oil.
Mix lemon juice with sour cream and extract.
Stream into batter.
Add dry ingredients to wet ingredients in mixer.
Mix just until incorporated. Batter will be thick.
Microwave a teaspoon of batter for 20-30 seconds. Taste for sweetness and lemon flavor.
Evenly divide in three six inch pans.
Bake at 325 degrees. Make sure to check at 25 minutes. You may need to bake ten more minutes. You may need to put foil over cake if it's browning too much and not done. Use thermometer to test inside center of cake. It will need to be 207 degrees F.
Cool completely in pan before removing, as this cake is tender.
Once cooled, remove from pan, and apply cream cheese frosting.