In a medium-sized skillet over medium heat brown the ground beef and drain out the grease. Transfer to the slow cooker.
To the slow cooker, add in the carrots, celery, garlic, diced tomatoes, red kidney beans, white cannellini beans, spaghetti sauce, tomato paste, salt, pepper, oregano, basil, thyme, and bay leaf. Stir.
Cover and cook on high for 3-5 hours or low for 5-7 hours or until the vegetables are tender.
Two ways to do the added pasta:
About 20 minutes before serving, boil the pasta until al dente. Reserve the water and drain.
Toss the pasta with red wine vinegar (optional; adds flavor/freshness, balances acidity of all the tomato)
Either add the pasta to the soup or serve on the side. I like to serve the pasta on the side so you can add what you want and then store (or freeze) the remainder of the soup without the pasta getting "soggy."
ALTERNATIVELY, (if you plan on eating this soup all in one day), you can add the uncooked pasta to the soup about 30 minutes before serving (turn heat to high).
Garnish with freshly grated Parmesan cheese and fresh parsley if desired.
This soup is extremely thick and hearty -- more of a stew-like consistency. We LOVE it this way, but if you prefer a "brothier" soup, add in some beef broth. OR add in some of the reserved pasta water and a cube or two of beef bouillon.