Preheat the oven to 400 degrees F. Place the chicken on a baking sheet and sprinkle it with the salt, pepper, garlic powder and basil. Drizzle (or spray) with olive oil. Bake for 20 minutes, or until the chicken is cooked through (internal temperature should be about 160 degrees F). Once cool, cut the chicken into cubes.: The oven heat brings a faint toasty aroma as the surface of the chicken browns and the seasoning crisps slightly, which adds savory notes to the final soup. You should hear a quiet sizzle as the oil warms and notice the edges becoming pale gold near the 10 to 12 minute mark. Allowing the chicken to rest briefly keeps the juices locked in, and cooling makes it much easier to cube neatly, which helps the pieces hold together when simmered in the broth. A common mistake is overbaking, which leads to dry chicken ; aim for the recommended internal temperature and check early if your oven runs hot.
While the oven is on, you can begin to make the mozzarella croutons too. Place the bread cubes on a baking sheet and drizzle with olive oil. Bake them for 8 to 10 minutes, or until slightly golden. Remove the baking sheet and cover the cubes in a slice of mozzarella. Return the sheet to the oven for 2 to 3 minutes, until the mozzarella is melty.: As the bread toasts, it releases a warm, bready aroma and the cubes develop a light crispness that contrasts beautifully with the melting mozzarella. The moment you pull the tray to top with cheese, you will notice the surface has firmed up enough to support the slice without collapsing. Returning them briefly to the oven ensures the cheese becomes glossy and slightly browned at the edges, creating that indulgent pull when you bite into a crouton. Avoid leaving them in too long, or the mozzarella can lose its tender melt and become rubbery.
Heat a large stock pot over medium heat and add the olive oil. Stir in the onion, garlic, salt, pepper and basil. Cook, stirring often, until the onions soften, about 5 to 6 minutes. Stir in the tomato paste and cook for 5 more minutes.: The pot will begin to smell richly aromatic as the onion sweats and the garlic softens, releasing sweet and savory notes that form the soup's foundation. The texture of the onion should transition from slightly translucent to tender, and you will see the tomato paste darken a shade as it toasts, which deepens its umami. Stirring prevents scorching and helps the flavors meld; if the heat is too high the aromatics can scorch and develop bitterness, so keep it moderate and patient.
Add in the chicken, diced tomatoes and Swanson Chicken Broth. Bring the soup to a boil. Reduce it to a simmer and add the pasta. Cook for 8 to 10 minutes (or slightly longer, depending on your cut of pasta), stirring occasionally. Stir in the parmesan cheese. Taste and season with more salt and pepper if needed.: When the pot first comes to a boil, you will hear a lively bubbling and see steam rise, carrying the tomato and broth aromas. Reducing to a gentle simmer lets the chicken warm through without shredding, while the pasta releases its starch, slightly thickening the broth. Stirring occasionally prevents the pasta from sticking and ensures even cooking; expect the broth to smell rich and slightly sweet from the tomatoes. Folding in the grated parmesan cheese at the end rounds the flavors with savory, nutty notes and gives a silkier mouthfeel. A frequent error is overcooking the pasta until it falls apart, so test early for al dente texture.
Ladle the soup into bowls and top with a mozzarella crouton (or two!). Sprinkle on some extra parmesan cheese and a few basil leaves. Serve immediately!: The final presentation is sensory gold; steam lifts the basil scent, and the visual pop of melted mozzarella on crisp bread invites that first spoonful. The sound of a spoon tapping a crisp crouton and the contrast between creamy broth and chewy pasta make the dish memorable. Serve quickly so the croutons retain some crispness, and offer extra grated parmesan cheese for those who want an extra savory finish. Watch that the croutons do not sit in the hot broth too long, or they will lose their texture.
