I've been making this forever, and everyone in my family loves it! It is a basic dish which definitely falls into "Comfort Food" category. In summer time, when there is plenty of tomatoes (and plenty of home-made tomato sauce!) use that home-made sauce instead of canned crushed tomatoes. And make sure you use LOTS of fresh basil! —Ausra
Sauce: coarsely chop onion, peeled carrots and celery stalks and process them in the food processor in 3-4 pulses, until finely chopped.
Heat the butter in a large pan or Dutch oven, add chopped vegetables and saute until soft, 2-3 min.
Add ground meat, or sausage to the pan and brown it, while breaking it with a spatula into small bits.
when the meat is all browned, add vinegar and cook until almost all liquid has evaporated.
Add crushed tomatoes to the pan, season with salt and pepper, cover the pan with the lid and let the sauce simmer on medium-low heat for 20-25 minutes.
Shells: first cook pasta shells in a plenty of salty water until almost cooked (you still want the shells to be a bit firm since they'll continue cooking when you bake them). Drain pasta and let it cool in colander while prepare the filling.
In a large mixing bowl mix ricotta, shredded mozzarella, egg, minced garlic, finely chopped basil, parsley, salt and pepper.
Assembling: pour the sauce into a large baking dish. I always use 9 x 13" Pyrex glass pan. Reserve about 1 1/2 cups of the sauce - you'll use it to top the shells.
Spoon ricotta filling into shells, place them on top of the sauce, seam facing up. Keep filling all the shells and laying them in snug rows. When the baking dish is full, spoon some of the reserved sauce on top of the shells. Cover the dish with a large sheet of aluminum foil and bake in 450 F oven for about 20-25 minutes until sauce is bubbly and the shells are heated through.
When ready to serve, garnish with some extra basil leaves - it will make the dish smell like heaven!