Preheat the oven to 350 degrees F (175 degrees C).
Mix Parmesan cheese and Italian seasoning together in a bowl. Coat chicken breasts in the mixture and arrange in an 8-inch square baking dish.
Melt butter in a skillet over medium-high heat. Saute garlic until tender, about 2 minutes. Whisk in flour to form a paste, about 3 minutes. Add cream; cook and stir until paste is thickened, about 7 minutes more. Season with salt and pepper. Add spinach; cook and stir until heated through, about 3 minutes.
Pour spinach mixture over chicken breasts in the baking dish; top with any remaining Parmesan cheese mixture.
Bake in the preheated oven until chicken is no longer pink in the center and the juices run clear, 30 to 45 minutes. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).
