Preheat broiler to high; position rack in center of oven. Spread butter over cut side of each roll. Place on foil-lined baking sheet; broil for about 1 minute or until bread is golden brown and toasted.
Spoon Refried Pinto Beans evenly onto each roll. Sprinkle with cheese, including edges. Broil for 3 to 5 minutes or until cheese melts and beans are heated through.
Top with avocados and Salsa Pico de Gallo. Serve immediately.
Note: Bolillos is a traditional bread from Mexico, but you can use crusty French bread or Italian rolls.