Mac and Cheese Soup

INGREDIENTS

• Kosher salt
• 3 3/4 cups fat-free low-sodium chicken broth
• 4 1/2-inch-thick slices baguette
• Freshly ground pepper
• Cooking spray
• 2 plum tomatoes, sliced 1/2 inch thick
• 3 shallots
• 1 stalk celery, cut into 1-inch pieces
• 4 ounces elbow macaroni (1 cup)
• 1/4 cup all-purpose flour
• 6 ounces shredded cheddar cheese (about 1 1/2 cups)
• 1 1/4 cups 2% milk
• 1 carrot, cut into 1-inch pieces
• 1/4 cup grated parmesan cheese