Tomato-Basil Parmesan Soup

Add tomatoes, celery, carrots, chicken broth, onions, oregano, basil (if using fresh oregano and basil, if using dried oregano and basil add it in the last hour of cooktime), and bay leaf to a large slow cooker. Cover and cook on LOW for 5-7 hours, until flavors are blended and vegetables are soft. About an hour before serving prepare a roux. Melt butter over low heat in a skillet and add flour. Stir constantly with a whisk for 5-7 minutes. Slowly stir in 1 cup hot soup. Add another 3 cups and stir until smooth. Add all back into the slow cooker. Stir and add the Parmesan cheese, warmed half and half, salt and pepper. Cover and cook on LOW for another hour until ready to serve.