Stuffed Mushrooms 12 large, fresh mushroom caps 1/3 lb. bulk sausage grated Parmesan cheese finelly chopped green onions Preheat oven to 400 degrees. Blanch the mushroom caps in boiling water for 2 minutes to remove the rough texture. Drain and allow to cool. Divide the sausage and mound in the mushroom caps. Place in a baking pan and sprinkle liberally with Parmesan cheese.sprinkle onions over top Bake in preheated oven for 8 to 10 minutes or until golden brown. If the mushrooms shrink, they are overdone