Melt butter in a skillet; add mushrooms, and sauté 10 minutes or until liquid has evaporated.
Process cream cheese and next 4 ingredients in a blender or food processor until smooth, stopping to scrape down sides. Stir in sautéed mushrooms; chill at least 2 hours.
Cut bread slices with a 2- or 2 1/2-inch shaped cutter. Spread mushroom mixture on bread. Garnish, if desired.
