There are four components to lasagne bolognese: the basic tomato sauce, the meat sauce, the béchamel sauce, and the lasagne. (Though you can buy a basic tomato sauce to eliminate one step, especially since you only need to add a 1/2 cup of it in the meat sauce.)
Make the Bolognese Meat Sauce first. While the sauce is simmering for the last
45 minutes, put the pasta water on high heat to boil and make the Mornay sauce.
Preheat the oven to 400 degrees.
The following is the preparation for fresh egg pasta. Iif you’re using a store-bought dry lasagne brand (which we don’t recommend, but understand if you must) follow the cooking instructions on the box.
Just as the water is about to boil, lay out some tea towels (or towels that won’t leave much fuzz on the lasagne sheets) and fill a large bowl with ice cubes to create an ice bath. When the water is boiling, add two healthy handfuls of coarse salt and stir to dissolve. Drop the lasagne in the water, one sheet at a time, for 30 seconds. Cool the pasta sheet briefly in the ice bath and lay on the towel to dry. Repeat until all the lasagne is cooked. Pat the pasta dry.
For lasagne assembly, butter a 9 1/2″-by-12″ baking pan. Lay one layer of pasta
down, then the meat sauce, and then the Mornay sauce. (Be careful not to overload the lasagne with large amounts of sauce. Authentic lasagne has multiple thin layers
of pasta with the sauces sparsely dispersed throughout.) Repeat this layering and finish with a sprinkling of Parmesan on the top to achieve a golden crust (feel free to add grated Parmesan among the layers, but remember the Mornay sauce already
Bake for 20 to 30 minutes or until golden and bubbling. Remove and let sit for a few minutes, and then serve immediately.