I would think if you want it to crisp up like the sides you would want to well grease or butter the pan. It looks like the oils from the cheese helped the sides out.
I have never made anything like this. It may be something I should look in to.
Made a Pizza lasagna last week. used no boil lasagna sheets, a larger jar of pasta sauce, cooked off a pound of sausage and added peppers and onions, had sandwich pepperoni I cut down some and used bagged pizza cheese. sauce, noodle, sauce, cheese, meats and cooked veggies. Repeat, I think I had 2 layers of filling with 3 layers of noodle topped with sauce and cheese. Baked it off at 375 for about 40 minutes in the counter top convection oven.