Preheat oven to 350 degrees F. In a mixing bowl, whip egg whites and frothy. Add cream of tartar and powdered erythitol. Whip until soft peaks form. Add Maple and Vanilla Flavoring. Whip until egg whites are semi-stiff. Stir together Stevia, Collagen, and oat fiber. Carefully mix the dry ingredients into the egg whites until combined. Fold in walnuts. Spoon batter into an angel food cake pan. Place on the lowest oven rack. Bake for 40 minutes. Remove from oven and turn cake upside down to cool for 4 hours. Carefully remove cake from pan be running a sharp knife along the edges of the cake pan. Icing: Melt butter and allow it to simmer until browned. Cool slightly. In a mixer bowl combine butter, erythitol, cream cheese, cream, Maple Flavoring, and Stevia. whip until smooth and creamy. Spread over cooled cake and garnish with chopped walnuts. Serves 12.
*I use a coffee grinder to powder the erythitol.
**There is a big difference in oat fiber, I will only use THM oat fiber. It is the best. I fluff up the oat fiber with a spoon and than spoon it into my measuring cup. Do not scoop it as that will pack it into the cup.
**You can over-beat egg white which will cause the cake to collapse after it has been baked. You want soft-medium-stiff whites. They should be soft mounds. This recipe fills my 6 quart mixer bowl almost full when they are fully whipped.