Set an oven rack about 6 inches from the heat source and preheat the oven's broiler.
2
Combine refried black beans, black beans, green chiles, garlic powder, chili powder, cayenne, salt, and pepper in a saucepan. Heat over medium heat until warm and combined, 3 to 4 minutes.
3
Place tostada shells on an ungreased baking sheet and evenly distribute bean mixture between them. Top with Monterey Jack cheese.
