Parmesan cheese Remove sausage meat from casings and crumble into a small skillet. Saut� gently, stirring often, until meat is thoroughly done. Season with fennel and, if desired, red pepper flakes. With a slotted spoon, remove sausage to a bowl, leaving the rendered fat in the skillet. Saut� onion and garlic in the fat, adding a little olive oil if necessary, until tender and golden, about 25 minutes. Stir in chopped parsley and add to reserved sausage meat. Stir (imported) olives and b�chamel into the sausage mixture; combine thoroughly. Taste the mixture and season with salt and pepper if necessary. Pull the stems off the mushrooms and save for another use. Wipe mushroom caps with a damp cloth and season lightly with salt and pepper. Fill each cap generously with the stuffing. Arrange caps in a lightly oiled baking dish. Sprinkle the tops of the stuffing with Parmesan cheese to taste. Bake at 450�F. for about 15 minutes or until bubbling and well browned. Let settle for 5 minutes before serving.