Heat oven to 325° F
Grease just the bottoms of four 8" round cake pans, then line the bottoms with parchment paper.
In a very large bowl, combine egg whites and cream of tartar.
With a hand mixer, beat the egg whites until thoroughly thickened to a smooth and glossy consistency.
In another very large bowl, combine the rest of the ingredients: egg yolks, tiger nut flour, sweetener, baking soda, melted fat, salt, and any additional flavorings you'd like to use. (See other possible additions in notes.)
Mix well with hand mixer.
Fold egg whites into the batter mixture. This is best done with about 1/4 of the fluff folded in at a time, very gently, until fully incorporated.
Divide evenly into the cake pans.
Bake at 325° for 20 minutes, or until firm but still spongy in the middle. Don't overcook!
Remove from pans and cool completely on baking racks. Cake releases from pan easily after running a butter knife around the edges. If allowed to cool in the pans, the texture is less enjoyable.
Frost with choice of frostings. I use either a 7-minute sugar-free frosting or Buttercream frosting made with ghee (I'll get a recipe posted ASAP. Pinkie swear.)