Slow Cooker Tomato Soup

Ingredients

• 2 15-ounce cans diced tomatoes ( )
• 1 10-ounce can tomato sauce ( )
• 1/4 cup fresh basil (finely chopped )
• 3 teaspoons minced garlic ( )
• 1 tablespoon salt ( )
• 1 teaspoon pepper ( )
• 1 Medium white onion (diced )
• 1 cup heavy cream ( )
• 4 cups chicken or vegetable broth ( )
• 2 cups shredded parmesan cheese ( )
• 3 tablespoons butter ( )
• 1/4 cup flour ( )