Preheat your oven to 375 degrees F (190 degrees C). Lightly grease a 9x13-inch baking dish with olive oil or cooking spray, coating the sides as well.

In a large mixing bowl, whisk together the egg whites and whole eggs for about 30 seconds until fully combined and slightly foamy.

Stir the cottage cheese and grated cheddar cheese into the egg mixture until fully incorporated. The mixture will look slightly lumpy from the cottage cheese but smooths out during baking.

Heat olive oil in a skillet over medium heat. Add the diced red and green bell peppers, chopped onion, and broccoli florets. Saute for about 5 minutes, stirring occasionally, until slightly softened but still holding their shape.

Add the chopped spinach to the skillet and cook for 2 more minutes until just wilted. Do not overcook as the spinach will continue cooking in the oven.

Transfer the cooked vegetables into the egg and cheese mixture. Season with garlic powder, salt, and black pepper. Stir well until everything is evenly distributed.

Pour the mixture into the prepared baking dish and spread evenly with a spatula. Bake for 30 to 35 minutes until the center is fully set and the top is golden. A toothpick inserted in the center should come out clean.

Let the bake rest for 5 minutes before slicing into squares. This helps the squares hold their shape cleanly. Serve warm.