1/4 cup loosely packed basil leaves, coarsely chopped
2 slices sandwich bread
1 cup whole milk
3/4 pound (300 grams) ground beef
3-1/2 ounces (100 grams) grated Grana Padano Riserva
1 large egg, lightly beaten
1 bunch fresh parsley, chopped
12 ounces (320 grams) uncooked spaghetti
Fry the chopped onion, celery and carrot in a saucepan with olive oil. Add the tomato passata, season with salt and add the basil. Cover and simmer on low heat for at least 30 minutes.
In a bowl, combine bread and milk and let stand 1 minute. Remove bread and gently squeeze to drain off excess milk; discard milk. Mix the soaked bread with the ground beef, Grana Padano Riserva, egg, parsley and a pinch of salt. Mix the ingredients together to combine. Wet your hands and form meatballs measuring ¾ inch (2 cm) in diameter. Cook in the sauce for at least 10-15 minutes.
In the meantime, bring a large pot of salted water to boil and cook the spaghetti until al dente, drain and toss with the sauce and meatballs. Serve immediately, sprinkled with additional grated Grana Padano Riserva.