Preheat oven to 180° C. Wrap a 5 cm high strip of double aluminum foil around the top edge of a 2 L soufflé dish: secure with a tape or string. Grease dish and foil with butter and sprinkle with parmesan or breadcrumbs. Set aside.
In a blender or a food processor, puree beans with milk until smooth.
In a saucepan, combine pureed beans, cheese, salt and cayenne. Cook and stir over medium heat until cheese is melted. Remove from heat. Beat in egg yolks one at a time.
In a large mixing bowl, beat egg whites until glossy and stiff peaks form.
Mix 60 ml of the beaten egg whites into the bean-cheese mixture, gently fold bean mixture into remaining whites.
Pour soufflé mixture into prepared dish. Bake about 35 minutes until golden brown. Serve at once.