Separate the eggs, and whip the whites with the cream of tartar for a few minutes until VERY stiff. Very slowly add in egg white protein. Fold the reserved yolks and seasonings to the whipped whites. Grease a bread pan very well. Spoon the mixture into the pan and smooth the top with a spatula. Bake at 325 degrees F for 30 minutes until lightly browned. Cool completely before cutting. Cut into 12 pieces. I also spread a little butter on each piece and rubbed with garlic cloves ( if not dairy sensitive sprinkle with Parmesan cheese). I tossed it back into the oven on a broiler for 3 minutes until the butter was bubbly and lightly browned.
STUFFING:
Preheat the oven to 325 degrees F. Sauté the celery, onion, and mushrooms in butter and spices until tender and translucent. Cut up the protein bread into small 1 centimeter cubes. Place the protein garlic bread cubes in the pan with the vegetable mixture. Add the broth and mix well (you can add more if desired). Season to taste with salt and pepper. Stir in the egg. Bake, covered, in a greased 1 1/2 to 2-quarts casserole for 35-40 minutes. Uncover and bake for 5-10 more minutes until golden brown on the top.