cheese-stuffed portobellos

My husband did not hesitate to declare these Hall of Fame!  I was almost too intent on describing how magnificent they were to hear him (he dove into the main dish first).  I can't say enough about these.  They are grand.  Gourmet.  Do I dare call them equisite?

cheese-stuffed portobellos (Food Network Magazine, June 2011)
cooking spray
4 6-inch portobello mushroom caps
4 cups spinach, chopped
1 cup panko breadcrumbs
1 cup shredded mozzarella
1 shallot finely chopped (I used 1 tablespoon white onion)
1 large tomato, diced
3 tablespoons grated pecorino romano cheese, plus some shaved for topping
3 tablespoons extra-virgin olive oil
kosher salt and freshly ground pepper
1/2 cup ricotta cheese

Preheat the broiler.  Mist a foil-lined broiler pan with cooking spray.  Put the mushrooms gill-side down on the pan; broil 5 minutes.
Meanwhile, toss the spinach, breadcrumbs, mozzarella, chopped shallot, tomato, 2 tablespoons each pecorino and olive oil, 1/2 teaspoon salt and pepper to taste in a medium bowl.
Remove the mushrooms from the broiler and turn them gill-side up on the pan.  Season with salt and pepper.  Mound the spinach filling on the mushrooms and top with the ricotta.  Sprinkle with the remaining pecorino and broil until the filling is heated through and the ricotta is lightly browned, about 5 minutes.
Divide the mushrooms among plates and drizzle with olive oil.