Preheat the oven to 375°F. Line a baking sheet with parchment paper and lightly grease it with cooking spray or butter.
Separate the egg whites from the yolks, placing the whites in a large mixing bowl and the yolks in a separate bowl.
Using an electric mixer, beat the egg whites on high speed until stiff peaks form, about 3-5 minutes.
Gently fold in the crumbled bacon, grated Parmesan cheese, chopped chives, salt, and black pepper into the whipped egg whites until just combined.
Spoon the egg white mixture onto the prepared baking sheet, creating 8 mounds. Make a small indentation in the center of each mound for the yolk.
Carefully place one egg yolk into the indentation of each egg white mound.
Bake in the preheated oven for 12-15 minutes, or until the egg whites are set and lightly golden.
Remove from the oven and let cool for a few minutes before serving.