Cook Italian Sausage: In a large pot, melt olive oil over medium-high heat. Add ground sausage, breaking it apart with a ladle. Cook covered, stirring occasionally, until browned and falling apart, around 5-7 minutes. Remove sausage from pot and set aside for later, but leave fat in the pot for the next step!
Sauté the Soffritto: Add onions, carrots, celery, garlic, oregano, parsley, basil, salt and pepper, and optional red pepper and cook covered over medium-high heat until onions turn translucent, around 5-7 minutes. Add tomato paste and stir until pasty, around 1 minute.
Build the broth: Return sausage, add cannellini beans, tomato sauce, diced tomatoes, chicken broth, bay leaves, and parmesan slices. Bring to a boil over high heat then reduce to low and simmer for 10-15 minutes, stirring frequently so parmesan does not stick to bottom of pot. Remove from heat, remove bay leaves, and let cool during next step.
Cook Pasta and Combine: In a separate small pot, bring 4 cups of water to a boil over high heat. Add ditalini pasta, reduce heat to medium-high, and simmer uncovered, stirring occasionally, for 8-10 minutes, or until al dente. Pour the pasta into a strainer in the sink, and into the pot. Stir, and serve!
