Preheat your oven to 400°F and line a small baking sheet with parchment paper.
Toss the diced red bell pepper and red onion with half of the olive oil and a pinch of sea salt.
Roast the vegetables for 15 to 20 minutes until they are tender and the edges are slightly caramelized.
While the vegetables roast, whisk the whole eggs, egg whites, garlic powder, remaining sea salt, and black pepper in a bowl until well combined.
Heat the remaining olive oil in a non-stick skillet over medium-low heat.
Add the roasted vegetables and baby spinach to the skillet, stirring for 1 minute until the spinach is just wilted.
Pour the whisked egg mixture into the skillet and let it sit for 30 seconds to begin setting.
Gently move the eggs with a spatula from the edges toward the center to create large, soft curds.
When the eggs are almost set but still look slightly moist, sprinkle the crumbled feta cheese over the top.
Remove the skillet from the heat and serve the scramble immediately while it is warm and fluffy.