Preheat the oven to 300°F (150°C). Grease a 5-by-9-inch loaf pan and line it with parchment paper. For rolls, prepare a parchment-lined baking sheet or a silicone mold pan instead.

Place the room-temperature egg whites and white vinegar in the bowl of a stand mixer. Alternatively, use a large mixing bowl and an electric hand mixer. Beat on high speed for approximately 10 to 15 minutes, or until firm, stiff peaks develop. Set the whipped egg whites aside.

In a separate bowl, combine the egg yolks, cottage cheese, baking powder, salt, whey protein powder, egg white protein powder, and allulose, when using. Add the vanilla extract only when preparing a French toast-inspired version.

Whisk the yolk mixture until thoroughly blended. For a smoother consistency, process the ingredients in a blender until uniform.

Add a small portion of the yolk mixture to the whipped egg whites. Fold gently, then continue incorporating the remaining mixture in small additions until evenly combined. Use light movements to preserve as much air as possible.

Transfer the batter to the prepared loaf pan. When making rolls, divide the mixture among the prepared molds or portion it onto the lined baking sheet. Sprinkle bagel seasoning over the surface, when desired.

Position the pan on the center oven rack and bake for 50 minutes. The bread is ready when the top is golden brown and a toothpick or skewer inserted into the center comes out clean.

Turn off the oven without opening the door. Leave the loaf or rolls inside the closed oven for an additional 10 minutes.

Remove the bread from the oven and allow it to cool slightly before serving. Enjoy it warm, toast it and add a small amount of butter, or let it cool completely before using it for sandwiches.