Preheat the oven to 375 degrees F. Line a baking sheet with parchment paper and set aside.
In a medium saucepan over medium-high heat, bring the milk, butter, and the 1/4 teaspoon salt to a boil. When the butter has melted, remove from the heat and add the flour all at once. Using a wooden spoon, beat the mixture vigorously until it forms a ball. Return to medium heat and continue stirring for 1 minute, or until the mixture dries. Remove the mixture from the saucepan and spoon it into a food processor. Let cool for 5 minutes. After it has cooled slightly, process for a few seconds. Add the eggs and cayenne and process for another 15 seconds, or until it is well combined. Transfer the mixture to a mixing bowl and let cool for 10 minutes. Stir in the cheese and bacon until they are just incorporated.
Scoop out 1 heaping tablespoon of dough and push it off the spoon onto a prepared baking sheet with a second spoon (or use your finger). Repeat with the remaining dough, spacing the mounds 2 inches apart. Sprinkle the tops of the puffers with fleur de sel. Bake for 30 minutes, or until browned and crisp. Serve warm.
Photograph by Chia Chong (c). Reprinted with permission from The Whole Hog Cookbook, by Libbie Summers, copyright (c) 2011. Published by Rizzoli.