Adjust rack in lower third of oven; preheat oven to 400 degrees. Grease and flour a large baking sheet. Cut the cheese into/4-inch cubes.
Bring the water and butter to a rolling boil in a saucepan. Add the flour all at once and stir vigorously with a wooden spoon until mixture is smooth and comes together in a ball. Transfer mixture to a bowl to cool slightly. Add eggs, 1 at a time, beating well after each addition. Add the bacon, parsley and cheese cubes.
Spoon the batter into a pastry bag fitted with a 1/2-inch plain pastry tip and pipe out small mounds, 1-inch in diameter (about 2 teaspoons each), on the prepared baking sheet. Leave about 1-inch space between each mound to allow for expansion. (Or spoon small mounds onto prepared baking sheet.).
Bake 25 to 35 minutes, or until golden. For crisper puffs, pierce sides with tip of paring knife, return to oven and bake 5 to 10 minutes longer.
Serve hot. Or cool on wire rack, store in a sturdy plastic container with a tight-fitting lid and freeze up to 2 weeks.
To recrisp, place frozen cheese puffs on a baking sheet in a preheated 325-degree oven until hot, about 10 minutes.