Melt the butter in a large saucepan over medium heat. Whisk in the flour and cook and stir for 5 minutes to slightly brown the mixture. Whisk in the broth. Increase the heat and cook and stir until thickened. Decrease the heat to low, stir in the half-and-half, and simmer for 20 minutes.
Stir in the marinara sauce, tomatoes, and basil, and cook until heated through. Season to taste with salt and pepper. Serve as is chunky-style, or puree in a food processor or blender if you prefer a smooth soup.
Can be made Meatless. Substitute vegetable broth for the chicken broth.