Preheat the oven: Set your oven to 375°F (190°C).
Place a 10-inch oven-safe skillet on the stove.
Whisk the eggs: In a large bowl, whisk the eggs until smooth. Stir in the cottage cheese, shredded cheese, salt, pepper, and seasoning if using. Mix until combined but don’t overbeat.
Sauté the veggies: Heat the olive oil or butter in the skillet over medium heat.
Add the onion and bell pepper. Cook for 4–5 minutes, stirring, until softened. Add the garlic and cook 30 seconds more.
Fold in the spinach and cook just until wilted.
Add the egg mixture: Reduce the heat to medium-low. Pour the egg mixture over the vegetables, tilting the pan to distribute evenly. Let it cook undisturbed for 2–3 minutes until the edges start to set.
Bake to finish: Transfer the skillet to the oven.
Bake for 12–15 minutes, or until the center is just set and no longer jiggly. A knife inserted in the center should come out mostly clean.
Rest and serve: Remove from the oven and let it rest for 5 minutes. Garnish with fresh herbs.
Slice into wedges and serve warm.