Stuffing -
1 1/2 tablespoons finely chopped yellow onion
2 tablespoon olive oil
6 ounces lean ground beef
Salt
1/2 cup chopped mortadella or smoked ham
1 egg yolk
1/2 teaspoon nutmeg
1 1/2 cups freshly grated Parmesan cheese
1 1/4 cups fresh ricotta

Meat Sauce -
1 tablespoon finely chopped yellow onion
2 tablespoon olive oil
6 ounces lean ground beef
1 teaspoon salt
1/2 cup canned Italian tomatoes, chopped, in juice

A sheet of homemade pasta dough -
2 eggs and 1 1/2 cups all-purpose flour
or packaged Manicotti shells
1 tablespoon salt
1/3 cup freshly grated Parmesan cheese
1/4 cup butter

Prepare the bechamel sauce. It should be rather thin, with a consistency similar to that of sour cream. Set aside.

For the stuffing, place the chopped onion in a saucepan or a skillet with the olive oil and cook over medium heat until translucent but not
colored. Add the ground beef, turn the heat down to medium low, and cook it without letting it brown. Crumble the meat with a fork as it cooks.
When it loses its raw red color, cook it for 1 minute more without browning. Transfer the meat with a perforated ladle or colander to a mixing bowl, carrying with it as little of the cooking fat as possible. Add 1 1/2 teaspoons salt, chopped mortadella, egg yolk, nutmeg, grated cheese, ricotta, and 1/4 cup of the bechamel sauce. Mix thoroughly. Taste and correct
the salt and set aside.
To prepare the meat sauce, place the chopped onion in a saucepan with the olive oil and saute over medium heat until very pale gold in color. Add the meat, turn the heat down to medium low, and cook without browning, exactly as you did for the stuffing. Add the salt and the chopped tomatoes and their juice and cook at the barest simmer for 45 minutes. Set aside.

Prepare the pasta dough, and, if you are making it by hand, make it as thin as possible. (The pasta machine has only one setting for thinness.) Cut the pasta into rectangles 3 inches by 4 inches. Do not allow it to dry
any longer than it takes to bring 4 quarts of water to a boil. While the water is coming to a boil, lay one or more clean, dry towels open flat on the work counter, and set a bowl of cold water not far from the stove. When the water comes to a boil, add the salt, then drop in 5 of the pasta strips. Stir with a wooden spoon. When the water returns to a boil, wait 20 seconds, then
retrieve the pasta with a large slotted spoon, dip it and rinse it in the cold water, then spread it on the dry towel. Cook all the pasta strips, no more than 5 at a time, in the same manner. When all the pasta is laid out on the towel, pat it dry with another towel. If using packaged manicotti, par boil the pasta just until pliable.

Preheat the oven to 400 degrees. Take a bake-and-serve pan 9" X 15" and butter the bottom. Lay a pasta strip flat and spread a tablespoon of stuffing on it, covering the whole strip except
for a 1/2 inch border all around. Roll the strip up on its narrow side, keeping it somewhat loose. Lay it in the baking pan with its
folded-over edge facing down. Proceed until you've used up either all the pasta or all the stuffing. Squeeze the cannelloni in tightly, if you have to, but don't over lap them. If stuffing ready-made pasta tubes, you may use a pastry bag to fill them. Spread the meat sauce over the cannelloni, coating them evenly with sauce.
Spread the bechamel sauce over this. Sprinkle with the grated cheese and dot with the butter. Bake on the next-to-highest rack in the oven for
15 minutes, or until a very light, golden crust forms. Do not in any case exceed 20 minutes, or it will be overcooked. Allow to settle for about
10 to 15 minutes before serve.