Preheat your oven to 300°F (150°C).
In a stand mixer or using an electric hand mixer, beat the egg whites and vinegar together until stiff peaks form (about 10–15 minutes).
In a separate bowl, mix egg yolks, cottage cheese, whey protein powder, egg white protein powder, baking powder, salt, and optional ingredients.
Gently fold the yolk mixture into the whipped egg whites, working slowly to keep the air in the batter.
Pour the batter into a parchment-lined and greased 9x5 inch loaf pan.
Bake in the center of the oven for 50 minutes or until a skewer inserted in the center comes out clean and the top is golden.
Turn off the oven and let the bread sit inside (door closed) for an additional 10 minutes.
Remove and cool completely before slicing into 12 servings.