Slow-cooker minestrone

Got this from a Better Homes and Gardens a while back. Serves 8, I often half it.

1 lb. cubed beef stew meat
2 14.5 oz cans diced tomatoes with basil, oregano, garlic
2 14 oz cans beef broth
1 15 oz can cannellini or great northern beans, drained and rinsed
1 15 oz can kidney beans, drained and rinsed
1 c thinly sliced carrots
salt and pepper to taste
1 c dry bow-tie pasta
1 medium yellow summer squash or zucchini, halved lengthwise and sliced

In crock pot combine everything EXCEPT pasta and squash. Cover and cook on low 8-9 hours or high 4-4.5 hours. Add pasta and squash, raise heat to high if necessary, cover and cook additional 30-45 minutes until pasta is tender. Top with parmesan cheese if desired.