Preheat the oven to 180°C (350°F).

Lightly oil a small ovenproof skillet or baking dish.

Beat the eggs in a bowl and season with salt, pepper, and dried oregano.

Chop the red onion finely and halve the cherry tomatoes.

Heat a drizzle of oil in the skillet over medium heat. Add the red onion and sauté until soft.

Add the spinach to the skillet and cook until wilted.

Pour the beaten eggs over the spinach and onion mixture. Evenly distribute the cherry tomatoes over the eggs.

Crumble the feta cheese on top of the egg mixture.

Transfer the skillet to the preheated oven and bake for 12-15 minutes, or until the eggs are set and the top is lightly golden.

Remove from the oven and let it cool for a few minutes before serving.