Preheat the oven to 200 ° C. Separate the egg white from the yolk. Be careful not to break the yolks. Beat the egg whites until stiff. Carefully fold in the cheese, bacon and chives. Line a baking sheet with parchment paper and place four clouds on it. Use a spoon to make a small pit in the middle of the clouds. Bake the clouds in the oven for 3 minutes. Take the tray out of the oven and place an egg yolk in the middle of the clouds. Season with salt and pepper. Bake for 2-3 minutes until the yolks have set.