Frittata con zucchine, patate e cipolle (la frittata di Fantozzi)

Frittata with Zucchini, Potatoes, and Onions (Fantozzi's Frittata) Serves 4: 4 eggs, 2 medium potatoes, 1 Tropea onion, 2 spring onions, 6 zucchini, grated Parmesan cheese, 4 sprigs of parsley, 2 sprigs of thyme (or marjoram), freshly ground black pepper, extra virgin olive oil to taste, salt to taste.