In a large soup pot, on medium-high heat, heat the olive oil and butter through until melted. Once heated, add in the onions, carrots, and celery and saute for 4-5 minutes. Once softened, add in the garlic and saute for an additional 30 seconds. Add the broth, tomatoes, parsley, potatoes, bay leaves, salt and pepper. Bring the soup to a boil, then add in green beans and corn. Reduce the heat to medium, and simmer until potatoes are nearly fork-tender, about 25-30 minutes. Add in the ditalini pasta 8-10 minutes before the end of cook time, so that the pasta is cooked al dente. Add the peas and cook an additional 5 minutes. Finally, add in the fresh spinach just before serving, allowing the leaves to slightly wilt. Serve hot and enjoy!