In a large Dutch oven or heavy soup pot, melt 2 tablespoons of butter with 1 tablespoon of olive oil over medium heat. Add the diced onion, grated carrots, and minced celery. Sauté for 5 to 6 minutes until tender and fragrant.

Add the minced garlic, dried thyme, rubbed sage, salt, and black pepper. Stir continuously for 1 minute until aromatic. Sprinkle the flour over the softened vegetables and stir vigorously for 1 to 2 minutes to cook out raw flour taste.

Slowly pour in the chicken broth while whisking steadily to prevent lumps. Whisk in the half-and-half (or heavy cream and milk). Bring the soup to a gentle simmer over medium-high heat, stirring frequently as the broth thickens into a rich, silky texture.

Add the shredded cooked chicken and the potato gnocchi directly into the simmering soup. Reduce heat to medium-low and simmer gently for 3 to 4 minutes until the gnocchi float to the surface and become tender and pillowy. Do not overcook.

Stir in the chopped baby spinach and grated Parmigiano-Reggiano. Simmer for 1 more minute just until the spinach wilts into deep emerald ribbons. Remove from heat, taste, and season with additional salt and black pepper if desired. Ladle into warm bowls and serve with crusty garlic bread!