Add the ground sausage and onion to a large pot over medium heat. Cook, breaking the sausage apart with a wooden spoon, until the sausage is browned and the onion softens. Let some of the sausage develop deeper golden edges for extra flavor.
1 lb (454 g) ground sausage, 1 medium yellow onion
Add the butter, flour, garlic, Italian seasoning, garlic powder, onion powder, salt, black pepper, and nutmeg. Stir continuously for 2 minutes, until the garlic smells fragrant and the flour is fully incorporated.
2 tbsps (28 g) butter, 2 tbsps (16 g) all-purpose flour, 4 cloves garlic, 1 tbsp (6 g) Italian seasoning, 1 tsp (3 g) garlic powder, 1 tsp (2 g) onion powder, ½ tsp (3 g) table salt, ½ tsp (1 g) black pepper, ⅛ tsp (0.5 g) freshly grated or ground nutmeg
Pour in the chicken stock and bring the soup to a boil. Reduce the heat to a simmer. Add the broken lasagna noodles and cook until the noodles are just tender, about 8 to 11 minutes.
8 cups (64 oz / 1.9 L / 1920 g) low-sodium chicken stock, 8 lasagna noodles
Reduce the heat to low. Stir in the shredded chicken, spinach, heavy cream, ricotta, mozzarella, and Parmesan cheese. Stir until the ricotta softens into the broth and the cheeses melt completely. Cook for another 2 minutes, until the spinach wilts.
4 cups (560 g) shredded cooked chicken, 4 cups (120 g) baby spinach, 1 cup (240 ml) heavy cream, 1 cup (245 g) whole milk ricotta cheese, 1 cup (113 g) shredded whole milk mozzarella cheese, 1 cup (100 g) shredded Parmesan cheese
Taste and adjust salt and pepper if needed. Serve hot with crusty bread and extra ricotta or black pepper on top if desired.