Create a slurry by combining 1/2 cup of the cold water, half and half and flour in a small bowl and whisk until well blended. Set aside.: The first sensory cue you notice is the slurry becoming glossy and smooth, with no visible flour granules, which signals it is ready to thicken the soup evenly. This matters because adding a lumpy slurry to a hot pot will produce an inconsistent texture, so whisk until silky and slightly viscous. If the slurry seems too stiff, add a teaspoon of cold water to loosen it, and if you see any specks, press the mixture through a fine mesh for assurance. A common mistake is using warm liquid here, which causes flour to clump, so always start cold and keep it aside until the right moment.
Heat a large pot or Dutch oven over medium heat and spray with oil then add the sausage. Cook the sausage, breaking up with a wooden spoon as it cooks, until no longer pink and slightly browned.: Listen for a steady sizzle as the sausage hits the hot surface, and watch the bits develop a golden brown, which adds caramelized savory notes to the soup. Browning is essential because it creates flavor compounds that enrich the broth. Break the sausage into small pieces so more surface area can brown. If the sausage steams instead of browns, the pan is overcrowded or not hot enough; work in batches or raise the heat slightly to get good color.
Add the shallots and garlic and cook until soft, 3 minutes. Add the tomato paste and chicken breast.: As the shallot softens, it will become translucent and release a gentle sweetness, and the garlic will aromatize the pot with heady, savory notes. Stir in the tomato paste and let it toast for a bit, its scent turning deeper and slightly caramelized, which amplifies umami. Nestle the chicken into the aromatics so it starts absorbing those flavors. Don’t let the garlic brown aggressively, because that introduces bitterness; soften it briefly before adding the paste and chicken .
Pour the remaining 1/2 cup water and chicken broth, parmesan rind, sundried tomatoes, Italian seasoning and bring to a boil. Partially cover and simmer on low until vegetables are soft and the chicken shreds easily, about 25 minutes.: The pot will transition from noisy boiling to a gentle simmer where savory steam rises and the aromas meld into a unified scent. The parmesan cheese rind slowly releases deep, salty undertones into the broth, and the sundried tomatoes impart concentrated sweetness. Simmering gently allows connective tissues in the chicken to loosen so it shreds tenderly. If the boil is too aggressive, you risk reducing the liquid too quickly and concentrating salt, so maintain a patient simmer.
Remove the chicken and set aside, shred with 2 forks.: When you lift the chicken out, it should yield under the forks with minimal resistance and steam will rise carrying rich, savory perfume. Shredding gives you bite sized pieces that distribute evenly in the bowl. If the meat resists shredding, it needs a few more minutes simmering; avoid shredding tough or undercooked meat as it will dry out in the soup.
Return the chicken to the pot then slowly stir in slurry, stirring well as you add and bring it back to a boil.: As you add the slurry in a thin stream, the liquid will gradually thicken and take on a glossy sheen, coating the back of a spoon, which is the correct consistency. This matters because a sudden thickening can make clumps, so pour slowly while whisking or stirring to integrate smoothly. If you notice small lumps forming, remove a ladle of hot liquid, whisk in the slurry off heat, then return it to the pot to rescue the texture.
Add the gnocchi, spinach, parmesan cheese and basil; cook according to package directions for the gnocchi, or until they start to float to the top and soup thickens. Adjust salt and pepper to taste, discard parmesan cheese rind and serve.: The gnocchi will begin to bob and float, a visual cue they are nearly done, and the soup will smell richer as the parmesan cheese melts into it. The spinach will wilt instantly, turning a vivid green and adding a fresh, slightly sweet taste. Taste and season carefully, because the sausage and parmesan cheese already contribute saltiness. Avoid overcooking the gnocchi, which makes them mushy, and be sure to remove the rind before serving to prevent an unpleasant chew.
