Cook lasagne noodles in boiling and salted water for 10-12 minutes, until al dente. Drain and rinse with cold water.
Meanwhile, cook spinach; drain.
For sauce, in a medium saucepan combine milk, cornstarch, and onion. Cook and stir till thickened and bubbly. Cook and stir 2 minutes more.
Spread 2 tablespoons sauce on the bottom of a 10x6x2 inch baking dish. Stir ham and italian seasoning into remaining sauce.
Arrange 3 lasagne noodles in the dish. Spread 1/3 of the sauce. Layer spinach atop. Layer another 1/3 of the sauce, the ricotta, and half of the mozzarella. Place remaining noodles atop. Top with the remaining sauce and mozzarella.
Bake at 375 degrees for 30 to 35 minutes or until heated through. Let stand ten minutes before serving.