If using raw chicken breast, place it in a medium saucepan and cover with chicken broth or water. Bring to a gentle simmer over medium heat and cook for 15-18 minutes until cooked through (internal temperature reaches 165°F). Remove, let cool slightly, and shred with two forks. Reserve the poaching liquid if desired — it can be added to the soup for extra flavor. If using rotisserie chicken, simply shred and set aside.

Heat olive oil in a large Dutch oven or heavy-bottomed pot over medium heat. Add the diced onion and celery and sauté for 4-5 minutes, stirring occasionally, until softened and translucent. Season with a pinch of salt as they cook.

Add the shredded carrots and minced garlic. Cook for another 2 minutes, stirring frequently, until the garlic is fragrant and the carrots begin to soften.

Sprinkle the flour over the vegetables and stir well to coat everything evenly. Cook for 1-2 minutes, stirring constantly, to cook out the raw flour taste. This step thickens your soup.

Slowly pour in the chicken broth while stirring continuously to prevent lumps. Add the dried thyme, Italian seasoning, black pepper, and red pepper flakes if using. Increase heat to medium-high and bring the soup to a gentle boil.

Reduce heat to medium-low and stir in the half-and-half. Allow the soup to simmer gently for 5 minutes, stirring occasionally, until it begins to thicken slightly. Do not let it boil vigorously after adding the half-and-half.

Add the shredded chicken to the pot and stir to combine. Add the gnocchi directly to the simmering soup. Cook for 3-5 minutes, stirring gently, until the gnocchi are tender and puffed up — they will float to the surface when done.

Stir in the baby spinach and cook for 1 minute until wilted. Taste the soup and adjust seasoning with salt and pepper as needed.

Remove from heat and serve immediately in warm bowls, garnished with cracked black pepper and fresh thyme if desired.