Clean mushrooms and remove stems. Set stems aside. Cook mushroom caps in butter
in a large skillet over medium-high heat, stirring constantly, for 5 minutes. Drain.
Place mushroom caps on rack of a broiler pan, stem side up. Set aside. Combine
sausage and garlic in a large skillet. Cook over medium-high heat until sausage
browns, stirring until it crumbles; drain well.
Position knife blade in food processor bowl; add mushroom stems, sausage mixture
and pepper. Process 20 seconds or until mixture is minced. Spoon mixture evenly
into mushroom caps; sprinkle with Parmesan cheese.
Broil 5 1/2 inches from heat for 3 minutes or until thoroughly heated.