Preheat oven to 375 degrees F.

Cook the pasta sheets in boiling, salted water until al dente. Shock the pasta in cold water. Lay the pasta out onto a clean kitchen towel and dry.

Take 1/2 of the melted butter and coat the bottom a 13 by 9 by 2-inch pan. Place a layer of pasta to cover bottom of pan. Ladle a thin layer of tomato sauce over the pasta, and sprinkle with 1/4 of the mozzarella. Add another layer of pasta sheets over the cheese. Ladle a thin layer of bechamel sauce over the pasta. Sprinkle 1/4 of the ground veal and 1/4 of the Parmigiano evenly over the bechamel. Repeat layering, until there are 3 layers of each. Add the final layer of fresh pasta and cover top layer with the remaining mozzarella, veal, Parmigiano and tomato sauce. Finally, ladle the remaining 1/4 cup of melted butter over the top and cover the pan with aluminum foil.

Bake approximately 30 minutes. Let stand for about 10 minutes before serving.

Tomato Sauce:

Saute the onion in olive oil until brown. Add the tomatoes and bring to a simmer. Crush tomatoes with a fork as they soften. Season with salt and pepper and add basil. Simmer for about 1 hour.

Bechamel Sauce:

Bring the milk to a simmer in a saucepot. In a saute pan, combine the melted butter with the flour to make roux. Whisk the milk into the roux. Bring to a simmer and cook for 2 minutes. Remove from the heat and set aside.

Ground Veal:

Melt the butter in a saute pan. Add the veal and cook until brown and cooked through. Season with salt, pepper, and nutmeg. Drain off excess liquid and set aside.