Preheat your oven to 400°F (200°C).
Line a baking sheet with parchment paper for easy cleanup.
In a large bowl, whisk the eggs and season with salt and pepper.
Spread the fresh spinach evenly on the baking sheet.
Arrange the sliced bell peppers and diced onion on top of the spinach.
Drizzle olive oil over the vegetables and toss to coat.
Create wells in the vegetable mixture and crack an egg into each well.
Sprinkle with additional salt, pepper, and cheese if desired.
Bake in the preheated oven for 15-20 minutes, or until the eggs are set.
Remove from the oven and let cool for a few minutes before serving.