Preheat oven to 400 degrees F. Rinse chicken and pat dry. work your fingers under the skin of the chicken to loosen.
Wash spinach and drain in colander. Blanch in a pot of boiling water. Drain into a colander and run cold water over to cool down. Squeeze out all the moisture and chop fine.
Saute the shallots in the olive oil over medium heat to soften. Add the spinach and the nutmeg and toss to coat. Mix with the ricotta and Parmesan cheese.
Stuff the mixture under the skin, working it in to evenly distribute.
Cut the lemon into quarters and stuff into the cavity of the chicken along with the sprigs of rosemary.
Tie the legs together and place in roasting pan. Season with salt and pepper and brush with the melted butter. Roast in the middle of the oven until the juices run clear, about one hour. Baste several times throughout the cooking process.
Transfer the chicken to a cutting board and allow to rest for 10 minutes before slicing. Tilt the pan and skim off the fat that has accumulated.
Remove the lemon from the cavity of the chicken and squeeze into the roasting pan. Scrape the bottom of the pan to loosen the browned glaze on the bottom. Slice the chicken and spoon the juices over the top.