I haven't made this, but I would brown as a precaution (it won't hurt). If it is baking in the oven for an hour (like a meat loaf), then reconsider, but if a pizza be safe and brown.
OK, I reread a little closer and it is like a thin meatloaf. And it says to cook it longer than the lasagna recipe, so I am going for it. Worst that happens is a cover it so the cheese does not brown and cook longer.
Definite 2 thumbs up on this recipe. My 18mo twins even ate it. Next time I think I will chop some spinach and mix it into the meat to pack a better vitamin punch. And I would add more garlic to the meat also, especially if using minced instead of chopping your own clove.