Preheat oven to 300°F (150°C) and place a baking pan filled with 1 inch of water on the bottom rack to create a steam environment.
In a blender, combine the liquid egg whites, cottage cheese, salt, black pepper, and garlic powder.
Pulse until the mixture is completely smooth and aerated.
Lightly grease a silicone muffin tray or egg bite mold with non-stick cooking spray.
Distribute the chopped spinach, diced red bell pepper, and shredded mozzarella evenly across the 12 muffin cups.
Pour the blended egg white mixture into the cups, filling each approximately 3/4 full.
Place the muffin tray on the middle oven rack above the water bath.
Bake for 20 to 25 minutes, or until the egg whites are set and no longer jiggle in the center.
Remove from oven and allow the bites to cool in the mold for 5 minutes before depanning.
Serve immediately or store in an airtight container for meal prep.