1 Cook pasta in plenty of boiling salted water until al dente, then drain, rinse and drain again.
2 Blanch tomatoes in boiling water for a few seconds. Drain, peel, quarter, core and cut tomatoes into small cubes.
3 Peel and chop onion and garlic. In a pot, sauté onion and garlic in hot oil. Add tomatoes, season with salt and pepper and simmer about 5 minutes.
4 Cut spaghetti into smaller pieces and mix with 1 tablespoon butter and Parmesan.
5 Beat the eggs and pour over pasta. Add tomatoes and mix well. Finely dice mozzarella and salami.
6 In a large nonstick skillet, heat 1 tablespoon butter. Add half of the egg mixture, top with mozzarella and salami cubes and cover with remaining egg mixture. Cook until eggs begin to thicken, about 10 minutes.
7 Gently slide frittata onto a large lid. Add remaining butter to pan. Flip frittata into pan and cook 5 minutes more. Serve sprinkled with parsley.