Place the eggs in a large pot in a single layer. Fill the pot with water to cover the eggs by about an inch. Cover and bring the water to a boil. Turn off the heat and let the eggs sit (covered) in hot water for 15 minutes. Drain. Cool the eggs under cool running water in the sink.
Peel the eggs and halve lengthwise. Place the cooked yolk in a medium bowl and place the white halves on a serving platter (cut-side up).
Mash the yolks with a fork. Add the bacon, mayonnaise, onion, sugar, vinegar, celery salt and pepper. Stir until thoroughly combined; taste and adjust/add seasonings, as needed.
Spoon the mixture into the egg white halves or use a piping bag with a large opening tip. Garnish with parsley. Refrigerate, lightly covered, until ready to serve.
Notes
*If preparing this recipe as GLUTEN FREE, be sure to use brands of mayonnaise and bacon that are known to be GF.*I always hard-boil a few more eggs than the recipe calls for in case of breakage during boiling. You can always use the left over to make egg salad sandwiches.