Prepare a 9 x 13 or deep 9”square baking dish with cooking oil spray.
Melt the butter in a medium sauce pan. Saute the onion and garlic until onion is soft and translucent.
Whisk in the flour and then add milk and chicken broth.
Add seasonings, bring to a boil and cook for about 1 minute.
Add the Fontina and Parmesan, stir to melt cheese and set sauce aside.
In a medium bowl combine the ricotta cheese, spinach and 1/4 cup Parmesan. Mix until combined.
Spread 1/4 of the cheese sauce in the bottom of the baking dish.
Top with 3-4 lasagna noodles, arranging in a flat layer.
Top with 1/2 of the chicken, 1/2 of the ricotta spinach mix, then top with another 1/4 of the sauce. Repeat.
Top the second layer with another layer of lasagna noodles and the rest of the sauce.
Sprinkle with a little more cheese on top. At this point the dish can be refrigerated overnight, covered with foil.
Bake at 350 for about 45 minutes, until bubbly and golden. If dish has been refrigerated adjust cooking time, it might need a little longer.