Clean mushrooms. Remove stems from mushrooms. Set stems aside. Lightly coat the rounded side of each mushroom cap with nonstick cooking spray. Place mushroom caps, stem sides down, in a 15x10x1-inch baking pan. Bake in a 425 degree F; oven for 5 minutes. Carefully place mushroom caps, stem sides down, on a double thickness of paper towels to drain while preparing filling.

Meanwhile, for filling, chop enough of the mushroom stems to make 1 cup. Coat an unheated large nonstick skillet with nonstick cooking spray. Preheat over medium heat. Add the 1 cup chopped mushroom stems, the broccoli, onion, garlic, dried oregano (if using), salt, and pepper to hot skillet. Cook and stir for 5 to 10 minutes or just until tender and most of the liquid is evaporated. Stir in feta cheese, bread crumbs, and fresh oregano (if using).

Place mushroom caps, stem sides up, in the same baking pan. Spoon the broccoli mixture into mushroom caps. Bake in the 425 degree F; oven for 8 to 10 minutes more or until heated through. Makes 20 servings.