Preheat your oven to 375°F and line a small rimmed sheet pan with parchment paper for easy cleanup.
Dice the red bell pepper and red onion, and slice the chicken apple sausage into thin rounds.
Place the peppers, onions, and sausage on the sheet pan, drizzle with olive oil, and toss to coat evenly.
Roast the vegetable and sausage mixture in the oven for 10 minutes until the vegetables begin to soften and caramelize.
While the vegetables roast, whisk the whole eggs, liquid egg whites, sea salt, black pepper, and garlic powder in a medium bowl until well combined.
Remove the pan from the oven, stir in the chopped baby spinach, and spread the ingredients into an even layer across the pan.
Carefully pour the egg mixture over the roasted ingredients, tilting the pan slightly if needed to ensure the eggs reach all four corners.
Return the pan to the oven and bake for 12-15 minutes, or until the eggs are completely set in the center and slightly puffy.
Allow the sheet pan to cool for 2 minutes before slicing the eggs into large squares or rectangles to serve.