Well I don't know where they are getting their mushrooms from but mine are always pretty dirty. It takes me forever to clean a box of them. And of course, they say not to wash them or they will absorb too much water and become soggy and rubbery. I digress.
Anyway portobello mushrooms can be used in any recipe calling for baby bellas or even white in some cases. Just cut them up to the same size as what the smaller mushroom would be.
This recipe is from ("big surprise") Giada DiLaurentiis. What can I say, she makes some good stuff...
3 tablespoons extra-virgin olive oil, plus extra for greasing the grill pan
4 to 6 portobello mushrooms
1/2 teaspoon salt
1/4 teaspoon freshly ground black pepper
1 cup marinara sauce (store bought or homemade)
1/2 cup shredded mozzarella cheese
1/4 cup grated Parmesan
2 tablespoons butter, cut into small pieces
Place a grill pan over medium-high heat or preheat a gas or charcoal grill.(Or preheat your broiler).
Drizzle 3 tablespoons of olive oil over both sides of the mushrooms. Sprinkle the mushrooms with salt and pepper. Drizzle olive oil on the grill to prevent the mushrooms from sticking. Grill until the mushrooms are heated through and tender, about 5 minutes per side.(I broiled mine for 5 minutes on each side.)
Preheat the oven to 400 degrees F.
Spread 1/2 cup of the marinara sauce on the bottom of a 9 by 13-inch baking dish. Place the grilled mushrooms on top of the marinara sauce and top with the remaining marinara sauce. Sprinkle with the cheeses and top with the butter pieces. Bake until the cheese melts and the top is golden, about 15 minutes. Serve.