Can't remember where I got this 'recipe' from, but it seems to work well:

Faux Atkins Bake Mix

1 cup soy flour
2 cups soy protein isolate
2 tablespoon baking soda
1 teaspoon salt
2 tablespoons Splenda
Sift together then store and use as you would Dr. A's. It's much cheaper
and things come out about the same.

**You could try substituting soya powder (milder taste) for the soy flour
and substituting egg protein for soy.
Soy flour can be purchased in most grocery stores in the bake section; soy
protein isolate is available in vitamin and health stores, I buy GeniSoy.
It is a different product, more refined, and can also be used for protein drinks. Be certain you purchase the soy protein isolate that indicates it can also be used for baking.