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.
Cream butter. Add sugar and beat until fluffy, about two minutes.
Add eggs one at a time. Mix each well.
Add lemon juice.
Add dry ingredients to wet ingredients.
Mix just until incorporated.
Bake at 350 degrees, 180 C, Gas 4, for 25 to 30 minutes. Make sure to check at 25 minutes.
You want to bake to golden brown.
Cool completely in pan before removing, as this cake is tender.
Once cooled, remove from pan, freeze for at least one hour before frosting cake.
You can freeze each cake separately, wrapped in plastic and frosted at another time.
If you're only freezing cake to frost, no need to cover.