Collard White Bean Potato Soup

1 tablespoon olive oil or butter
1 small onion, chopped
1 stalk celery, chopped
1 medium carrot, sliced
1 bay leaf
1 large yellow or red potato, cubed
4 cups coarsely chopped collard greens
1 quart vegetable or chicken broth
1/2 teaspoon dried thyme or 1 teaspoon fresh thyme leaves
1 15 oz. can cannellini beans, drained & rinsed
salt & pepper, to taste
Optional: fresh grated Parmesan cheese

1. Melt the butter in a large saucepan over medium heat. Add the onion, celery, carrot, and bay leaf, and sauté about 5 minutes, until veggies soften.
2. Stir in the potatoes, collard greens, broth, and thyme. Season with salt. Bring to a boil, reduce heat, and simmer until potatoes and collard greens are tender, about 15 minutes. Add the cannellini beans and continue cooking until heated through, another 5 minutes or so. Season with pepper and more salt if needed. Remove bay leaf. Serve sprinkled with fresh Parmesan cheese, if desired.