Preheat oven to 350 degrees F (175 degrees C). Arrange phyllo cups on an ungreased baking sheet.
In a large skillet over medium heat, melt butter and combine sausage meat and garlic. Cook until sausage is browned, about 5 to 8 minutes; drain grease, and add mushrooms. Stirring occasionally, cook 5 minutes more or until all liquid evaporates; remove from heat and let cool.
Fill each phyllo cup with 1 tablespoon of the sausage mixture, and top with a pinch of cheese. Bake in a preheated oven 10 to 12 minutes, or until the cheese melts and the pastry is golden brown. Serve immediately.