Preheat the oven to 375 degrees F (190 degrees C).
Place bacon slices on a microwave-safe plate between 4 sheets of paper towels. Microwave until sizzling and browned, about 4 minutes. Let cool for 10 minutes; chop.
Cook Italian sausage over medium-high heat in a 15-inch frying pan or large pot until browned, about 5 minutes.
Reduce heat to medium. Add onion and cook until softened, about 2 minutes. Stir in garlic and cook until fragrant, about 1 minute. Mix in flour. Pour in chicken broth and bring to a boil. Reduce heat and simmer until thickened, about 5 minutes. Fold spinach in carefully, stirring until wilted, about 2 minutes. Add gnocchi and heavy cream, stirring mixture until thoroughly combined.
Transfer mixture into a 9x13-inch baking pan. Top with bacon pieces and Parmesan cheese.
Bake in the preheated oven until cheese is golden brown, about 30 minutes. Season with salt and pepper.
