Preheat oven to 400 degrees F.
Spray a 9 x 13" baking dish with cooking spray.
Bring the chicken broth to a boil over medium-high heat in a medium sized saucepan.
Add the orzo and cook until almost tender, about 7 minutes.
Melt the butter over medium heat in a medium skillet.
Add the onion and saute until tender, 3 minutes.
Add the garlic and saute for another minute, do not burn.
Add mushrooms and continue to saute until golden around the edges, around 7 minutes.
Add Marsala wine.
Scrape the brown bits off bottom of the pan and cook until Marsala is reduced by half, about 5 minutes.
Add mushroom mixture to the orzo in a large bowl.
Add the cream, fontina and mozzarella cheeses, peas, salt and pepper.
Stir to combine.
Pour the mixture into the prepared baking dish.
In a small bowl, combine bread crumbs, Parmesan, and thyme.
Sprinkle the bread crumb mixture over the top of the pasta/mushroom/pea mixture.
Bake until golden brown on top, 25 minutes.
I also broiled it for 3 minutes to get the top more golden brown.