Crock Pot Minestrone Soup

Name: Crock Pot Minestrone Soup
Ingredients: olive oil, optional; 1/2 cup sweet yellow onion, minced; 4 large garlic cloves, minced; 2 cups zucchini, small chopped; 2 cups russet potato, small chopped; 1/2 cup small chopped carrots; 1 cup kernel corn; 1 cup green beans; 1 can great northern beans; 8 cups vegetable stock; 2 cups canned diced tomatoes; 1 1/2 tablespoons tomato paste; 1 teaspoon salt; 1/2 teaspoon pepper; 1/2 teaspoon Italian seasoning; 1/2 pound ditalini pasta; 4 cups baby spinach