- Warm the shallow half of a frittata pan over medium-high heat. Scatter the pecorino romano in the pan in an even layer and cook until golden and crisp underneath, about 2 minutes. Turn the cheese over and cook until golden on the other side, about 2 minutes more. Crumble the cheese into large shards and place in a small bowl. Stir in the parsley. Set aside.
- Warm the deep half of the frittata pan over medium-high heat. Cook the pancetta, stirring occasionally, until crisp, 7 to 8 minutes. Transfer to a paper towel-lined plate. Wipe out the pan with paper towels.
- In the deep pan over medium heat, warm 1 tablespoon of the olive oil. Add the onion and cook, stirring occasionally, until softened, 6 to 7 minutes. Add the artichokes and cook, stirring occasionally, for 2 minutes. Add the garlic and cook, stirring frequently, for 1 minute. Add the spinach and cook, stirring occasionally, until wilted, 3 to 4 minutes. Transfer to a bowl and add the pancetta and mozzarella. Stir in the eggs and season with salt and pepper.
- In the deep pan over medium heat, warm 2 teaspoons of the olive oil. Add the egg mixture and cook, using a rubber spatula to lift the cooked edges and allow the uncooked eggs to flow underneath, until the eggs are just beginning to set, 6 to 7 minutes.
- Meanwhile, in the shallow pan over medium heat, warm the remaining 1 teaspoon olive oil. Place the shallow pan upside down on top of the deep pan and flip the frittata into the shallow pan. Cook, covered, until the eggs are set, 8 to 9 minutes.
- Carefully slide the frittata onto a plate. Sprinkle with the pecorino mixture and serve with lemon wedges.