2 pounds processed cheese food (such as Velveeta®)
¾ pound cooked and peeled whole crawfish tails
24 brown and serve pistolette rolls
2 quarts vegetable oil for frying
Melt the butter in a saucepan over medium heat. Stir in the onion and cook until the onion has softened and turned translucent, about 5 minutes. Pour in the evaporated milk, cheese, and crawfish tails. Cook and stir until the cheese has melted and the sauce is smooth, about 5 minutes more. Use the end of a spoon to poke a hole into each pistolette roll. Fill each roll with about 1 tablespoon of the crawfish filling.
Heat oil in a deep-fryer or large saucepan to 375 degrees F (190 degrees C).
Fry the rolls a few at a time in the hot oil until golden brown, about 3 minutes. Drain on a paper towel-lined plate and serve hot.