Preheat the oven to 375°F (190°C). Place a rack in the center.
Heat olive oil in a cast iron skillet over medium heat.
Add onion and cook 5–6 minutes until softened.
Stir in garlic and cook 1 minute, until fragrant.
Add spinach and stir until just wilted. Remove skillet from heat.
In a large bowl, whisk eggs, ricotta cheese, Parmesan, paprika, pepper, and a pinch of salt until smooth.
Pour the egg mixture into the skillet over the spinach and onion. Stir gently to distribute.
Place skillet in the oven and bake 20–25 minutes, until the center is set and the top is lightly golden.
Let rest 5 minutes. Slice and serve warm, garnished with parsley or basil.