Cut off tentacles so that you have just the body cavity. Make sure to keep it whole so you can stuff it without leaks. Reserve the tentacles.
Mix together the ricotta, spinach, Parmesan, pepper, nutmeg, parsley and egg. Set aside.
Heat the oil at medium in a large heavy skillet or saucepan.
Add the garlic. Stir and cook for a few seconds. Add the tomatoes. Bring to a boil and add tomato paste. Lower heat and add rosemary. Simmer sauce for 25 minutes, stirring occasionally.
While the sauce is simmering, stuff the body of each squid only about 1/3 full of the spinach/cheese mixture. If you overstuff them, they will explode. You might also want to poke a hole or two in the body of the squid. Fasten the opening of each squid with a toothpick.
After the sauce has cooked, place the stuffed squid in the simmering sauce. Add the tentacles to the sauce. Simmer for 3 to 4 minutes. Then turn carefully and simmer for an additional 3 minutes.
While the squid is cooking, melt the butter in a clean pan and toss the pine nuts in the butter until golden. Watch carefully; pine nuts have a tendancy to burn.
Lift out stuffed squid to a warm, flat serving dish with sides. Spoon sauce around and garnish with pine nuts.