Preheat your oven to 300°F (150°C). Line a baking sheet with parchment paper or a silicone baking mat to prevent sticking.
In a clean, dry bowl, beat the egg whites with cream of tartar until stiff peaks form. This process is crucial for achieving the light and airy texture characteristic of cloud bread.
In a separate bowl, whisk together the egg yolks, softened cream cheese, baking powder, salt, apple cider vinegar, and any optional seasonings until smooth and well combined.
Gently fold the egg whites into the egg yolk mixture, being careful not to deflate the whites. The batter should be light and airy.
Spoon the batter onto the prepared baking sheet, forming 8 equal-sized rounds. Use the back of a spoon to smooth the tops and create a slight indentation in the center of each round.
Bake for 25-30 minutes, or until the cloud breads are golden brown and firm to the touch.
Allow the cloud breads to cool on a wire rack before serving. This step helps them firm up and enhances their texture.