Preheat your oven to 375°F (190°C) and line a small rimmed sheet pan with parchment paper.
Place the diced bell peppers, finely chopped broccoli florets, and diced red onion on the sheet pan.
Drizzle the vegetables with avocado oil and toss to coat evenly, spreading them into a single layer.
Roast the vegetables in the oven for 10-12 minutes until they are tender and just starting to brown.
While the vegetables roast, whisk together the whole eggs, egg whites, sea salt, black pepper, and garlic powder in a medium bowl until well combined.
Remove the sheet pan from the oven and ensure the vegetables are spread out evenly across the pan.
Carefully pour the egg mixture over the roasted vegetables, ensuring the liquid reaches all corners of the pan.
Return the pan to the oven and bake for an additional 12-15 minutes, or until the eggs are completely set and the edges are lightly golden.
Let the eggs cool for a few minutes before slicing into squares and serving.