Prep the pan: Heat the oven to 350°F (175°C). Grease a 9x9-inch baking dish or a 9x13-inch if you prefer a thinner bake and faster cooking.
Sauté veggies: Warm a little oil or butter in a skillet over medium heat.
Cook onions and mushrooms first until moisture evaporates, then add peppers and finally spinach. Season lightly with salt and pepper. Set aside to cool slightly.
Blend the base: In a blender, combine eggs, cottage cheese, and Greek yogurt or milk.
Blend until completely smooth and frothy, 20–30 seconds.
Season: Add garlic powder, onion powder, salt, and pepper to the blender. Pulse a few times to combine.
Layer the dish: Spread the sautéed veggies and cooked protein evenly in the baking dish. Sprinkle on the shredded cheese and Parmesan.
Pour and bake: Pour the egg mixture over everything.
Tap the pan gently to remove air bubbles. Bake for 28–35 minutes (closer to 22–28 minutes if using a 9x13), until the center is just set and the top is lightly golden.
Rest and slice: Let it rest for 10 minutes before slicing. Garnish with fresh herbs if using.