Cannelloni Filling: Sauté ground beef with onion, sage and rosemary until meat is browned and crumbly. Add salt and white wine and cook until wine evaporates.
Béchamel sauce: Melt 4 butter in saucepan, then add flour and stir thoroughly. Stir in milk and bring to a slow boil until mixture thickens. Stir into the meat mixture and mix well. Stir in the mozzarella and egg yolks; set aside.
Sauté onions in melted butter until soft and translucent. Add ½ cup white wine and let it cook down to evaporate; add tomato and salt. Mix well; simmer for 15 minutes.
Boil pasta in salted water, a few at a time, and cook for 8 to 10 minutes or until al dente. Using a slotted spoon, transfer to cold water then put on a flat surface.
Preheat oven to 400º. Spoon a line of filling into each shell, starting from one end and using your finger to push the filling inside of each shell.
Place cannelloni in a 9x13 inch baking dish and cover with tomato mixture.
Bake for 15 minutes. Stand for 5 minutes and serve.
