1. Peel the garlic. Place garlic and chili in the bowl fitted with the ultrablade knife. Mince at speed 11 for 10 seconds.
2. Cut the pancetta into small pieces. Replace the ultrablade knife with the mixer and add oil and pancetta. Launch the P1 simmer program at 270°F for 10 minutes.
3. At the end of the program, add tomatoes, salt and pepper. Launch the P2 simmer program at 200°F for 35 minutes, with the stopper.
4. Cook the spaghetti in a large saucepan according to package directions.
5. Pour sauce over the pasta and add cheese. Mix and serve.