In a deep pan, sauté onions, celery, and carrots in olive oil for 5 minutes. Add ground meat and cook until the meat is no longer pink. Drain any fat.

Add wine and simmer 8—10 minutes, or until evaporated. Add milk next and simmer 8—10 minutes, or until evaporated. Stir in tomato paste and Italian seasoning.

Next, crush and add the tomatoes, with the juice, to meat mixture. Add bay leaf, cover, and simmer on low for 45 minutes.

While Bolognese sauce is simmering, heat milk in a saucepan on medium. Melt butter ina small skillet. Once melted, stir the flour into the butter until smooth. Continue stirring as the flour cooks to a light, golden, sandy color, about 5 minutes.

Slowly whisk the roux into milk. Bring to a gentle simmer, then reduce heat to medium-low and continue simmering until the flour has softened and no longer tastes gritty, 10 to 15 minutes, then season with salt, pepper and nutmeg.

Preheat oven to 400°F.

In an 8- by 12-inch lasagna pan, put a thin layer of Bolognese on the bottom. Next, place lasagna sheets and cover with a layer of Bolognese. Add another layer of lasagna sheets topped with bechamel. Sprinkle 1 cup of mozzarella and 1 cup of parmesan over the bechamel. Repeat layers so you end up with 3 layers of each.

Cover with foil and bake for 45—50 minutes. Remove foil and set oven to broil. Broil the lasagna until the cheese is golden brown (about 2 minutes). Remove from the oven and allow to cool for 20 minutes before slicing into it.