Preheat the oven to 400˚F. Butter a (9 by 12-inch) baking pan.
Bring the chicken broth to a boil over medium-high heat in a medium saucepan. Add the orzo and cook until almost tender, about 7 minutes. Pour the orzo and the broth into a large bowl. Set aside.
Meanwhile, melt the butter over medium heat in a medium skillet. Add the onions and sauté until tender, about 3 minutes. Add the mushrooms and sauté for about 5 minutes. Add the wine and cook until the wine has reduced by half, about 5 minutes. Add the mushroom mixture to the orzo in the large bowl. Stir in with cream, Fontina, mozzarella, peas, salt and pepper. Pour the mixture into the prepared baking dish.
In a small bowl combine the bread crumbs and Romano, sprinkle on top of the pasta. Bake until golden, about 25 minutes.