Heat butter or oil in heavy saucepan. Add onions and garlic and cook for 5 min.
Add red crushed pepper and saute for 30 sec.
Add tomatoes. Simmer until the sauce is reduced and mash some of the tomatoes (~ 1 hour). In the meantime, you can start to cook the penne pasta.
Season with salt, pepper, and sugar to taste. Add 1 cup chopped fresh basil. Mix and cook for another 5-10 minutes on low heat.
To Prepare Pasta:
Boil the Penne Pasta al dente.
Add the pasta to the sauce. I usually like a generous serving of sauce compared to my pasta. Top the pasta with freshly ground black pepper and garnish with fresh chopped basil. Serve hot with home-made garlic bread.
Notes
Gluten-free Option - use your favorite GF pasta such as brown rice pasta, quinoa pasta, or lentil pasta.