Peel garlic and dice finely. Chop the ham finely. Cook pasta with leek in boiling salted water for about 10 minutes. Heat the oil in a pot and fry the ham. Take out, fry garlic in frying fat.
Add tomato sauce, season with pepper and sugar and simmer for 5 minutes. Drain the pasta and leek, drain. Add ham to the sauce, season again. Serve the pasta with the sauce, garnish with basil