2 tablespoons olive oil
1 ½ pounds Italian sausage
1 onion, diced
2 carrots, diced
2 celery ribs, diced
4 garlic cloves, minced
1 ½ teaspoons kosher salt
½ teaspoon freshly ground black pepper
1 teaspoon dried oregano or 1 tablespoon minced fresh oregano leaves
6 cups chicken broth
1 (28-ounce) can diced tomatoes
2 (15 ½-ounce) cans cannellini beans, drained and rinsed
4 loosely packed cups spinach
½ cup freshly grated parmesan, for serving
Heat two tablespoons of the olive oil in stockpot over high heat. Add the sausage and cook, stirring frequently, until it is cooked through and nicely browned. Transfer the sausage to a paper towel-lined plate.
In a slow cooker, combine the sausage, onion, carrots, celery, garlic, salt, pepper, oregano, broth, tomatoes, and beans.
Cover and cook on low for 6 hours or on high for 3 hours.
When the soup is done cooking, add the spinach and stir until it wilts.
Ladle the soup into serving bowls and garnish with the cheese.