Preheat your oven to 375°F (190°C) so it is hot and ready when the skillet is prepared.
Dice the onion, bell pepper, and potatoes into small, even pieces (about 1/2-inch cubes). Chop the spinach and mince the garlic.
1 small yellow onion, 1 red bell pepper, 2 small potatoes, 2 cups fresh spinach, 2 cloves garlic
Place a 10–12-inch oven-safe skillet over medium heat and add the olive oil. Warm for about 1 minute until the oil shimmers but does not smoke.
2 tablespoons olive oil
Add the diced potatoes and a pinch of salt to the skillet. Cook, stirring every couple of minutes, for 8–10 minutes, until they start to brown and become just tender. If they stick, add a small splash of oil or a tablespoon of water.
2 small potatoes, 1/2 teaspoon salt
Stir in the diced onion and bell pepper. Cook for 5–7 minutes, until the onion is soft and translucent and the pepper is slightly tender.
1 small yellow onion, 1 red bell pepper
Add the minced garlic, smoked paprika, dried oregano, salt, black pepper, and red pepper flakes (if using). Cook for 30–60 seconds, stirring, until the garlic is fragrant but not browned.
2 cloves garlic, 1/2 teaspoon smoked paprika, 1/2 teaspoon dried oregano, 1/2 teaspoon salt, 1/4 teaspoon black pepper, 1/4 teaspoon red pepper flakes
Add the chopped spinach to the skillet and cook for 1–2 minutes, stirring, until it wilts and mixes with the vegetables. Taste and adjust seasoning with a little more salt and pepper if needed. Turn off the heat.
2 cups fresh spinach, 1/2 teaspoon salt, 1/4 teaspoon black pepper
In a medium bowl, whisk together the eggs, milk or half-and-half, and Parmesan (if using) until smooth and slightly frothy.
8 large eggs, 1/4 cup milk, 2 tablespoons Parmesan cheese
Sprinkle about 3/4 cup of the shredded cheese over the vegetable mixture in the skillet, reserving the remaining 1/4 cup for topping. Gently stir to distribute the cheese evenly.
1 cup shredded cheese
Pour the whisked egg mixture evenly over the vegetables and cheese in the skillet. Tilt the skillet slightly if needed so the eggs reach all the edges.
8 large eggs, 1/4 cup milk, 2 tablespoons Parmesan cheese
Sprinkle the remaining shredded cheese evenly over the top of the egg mixture.
1 cup shredded cheese
Transfer the skillet to the preheated oven and bake for 12–16 minutes, until the eggs are just set in the center. They should no longer look liquid but may have a slight jiggle; they will firm up as they rest.
Remove the skillet from the oven and let it rest for 5 minutes. Garnish with chopped fresh herbs, slice into wedges or scoop into portions, and serve warm.
fresh herbs