1. Bring milk to a boil in a large saucepan with butter, salt, cayenne, and white pepper. Slowly add flour, whisking constantly and vigorously until the mixture begins to pull away from the sides of the pan, about 5 minutes.

2. Cover an 11-by-17-inch baking sheet with plastic wrap. Pour mixture onto three quarters of the prepared baking sheet, spreading evenly with an offset spatula. Cover with plastic wrap, and transfer to refrigerator to chill until firm, about 1 hour.

3. In a large, deep pot, heat 4 inches of oil until it reaches 350 degrees. Remove plastic wrap, and cut dough crosswise into 3-inch strips. Cut strips crosswise into 1/2-inch fries. Transfer fries to heated oil, and fry in batches until golden, about 2 minutes. Remove from oil, and season with salt and cayenne pepper. Repeat with remaining fries. Serve immediately.