Slow Cooker Tomato Basil Soup

Slow Cooker Tomato Basil Soup
2- 14 oz cans diced tomatoes
1 c diced celery*
1 c diced carrots*
1 c diced onions*
4 c broth (vegetable or chicken)
1 t oregano
1 T basil
1 bay leaf
1/2 c butter
1/2 c flour
1 c Parmesan cheese
2 c warm half & half
salt and pepper, to taste

1. Place tomatoes, celery, carrots, onions, broth, oregano, basil, and bay leaf in a large slow cooker; cook on low for 6-8 hours.
2. About 45 minutes before you plan on serving, melt butter in a pan and add flour; stir until well mixed. This is called a roux.
3. Slowly add a cup of the soup to the roux; add more soup until the roux is well incorporated.
4. Add roux mix in to slow cooker; stir in cheese, and half & half.
5. Cook on low for another 30 minutes before serving. Salt and pepper as desired.
*Cut all vegetables about the same size so that they cook at the same rate.