As you expand the well, keep pushing the flour up from the base of the mound to retain the well shape. The dough will come together when half of the flour is incorporated.
Start kneading the dough with both hands, using the palms of your hands. Once you have a cohesive mass, remove the dough from the board and scrape up and discard any leftover bits. Lightly reflour the board and continue kneading for 6 more minutes. The dough should be elastic and a little sticky. Wrap the dough in plastic and allow to rest for 30 minutes at room temperature. Roll or shape as desired.
Roll the pasta out to the thinnest setting on a pasta rolling machine and cut it into rectangles measuring 4 inches by 6 inches. Divide the meat filling evenly among the rectangles and roll the pasta around the filling, jelly-roll style making 14 to 16 canneloni. Blanch until tender in boiling water. Remove and put in an ice water bath. In an 8 or 9-inch square, oven-proof casserole, spoon half the tomato sauce across the bottom in an even layer. Carefully lay each pasta package in the casserole so that they are in a single layer. Top with the remaining tomato sauce, then the bechamel. Finish with the freshly grated Parmigiano-Reggiano and bake in the oven 20 to 25 minutes, until the sauces and cheese are bubbling and the edges of the pasta are crispy and browned. Serve immediately from the cooking dish.
Meanwhile, heat milk in separate pan until just about to boil. Add milk to butter mixture 1 cup at a time, whisking continuously until very smooth and bring to a boil. Cook 10 minutes and remove from heat. Season with salt and nutmeg and set aside.
Yield: 3 cups