Combine first 4 ingredients and ¼ cup mozzarella cheese; set aside. Preheat oven to 375°. Remove stems from mushrooms, and place cap side down on a lightly greased baking sheet. Roll cream cheese mixture into balls small enough to fit into mushrooms. Fill each mushroom with a mini cheese ball; sprinkle with remaining mozzarella cheese. Bake 10-15 minutes or until bubbly and browned. Makes 6-8 servings.