Preheat your oven to 300°F (150°C) and line a baking sheet with parchment paper.
In a large mixing bowl, beat the egg whites with cream of tartar until stiff peaks form.
In another bowl, mix together the egg yolks, softened cream cheese, and sea salt until smooth.
Gently fold the beaten egg whites into the egg yolks mixture until just combined. Be careful not to deflate the egg whites too much.
Spoon the batter onto the prepared baking sheet, forming small rounds about 3 inches in diameter.
Bake in the preheated oven for 20-25 minutes, or until the cloud bread is golden brown and set.
Remove from the oven and let cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.
Serve the cloud bread as desired. It can be enjoyed plain, as a sandwich bread, or topped with your favorite spreads and toppings.
Notes
I recommend lining the baking tray with parchment paper; otherwise, the cloud bread will stick and be difficult to remove. A silicone baking mat also works if you have one, but I prefer parchment paper.
Use large eggs, not small or medium, for the best results. Separate the eggs carefully, making sure no yolk gets into the whites. Even a small amount of yolk can stop the egg whites from whipping up properly.
Cream of tartar is naturally gluten-free as it's a byproduct of fermented grapes. However, some brands do manufacture it in facilities that also process wheat products. I suggest checking the label for this information and choosing a brand that's certified gluten-free.
The egg whites are whipped until stiff peaks form, which means they hold their shape when the whisk is lifted. I also test this by turning the bowl upside down - if the whites stay in place, then they're ready.
Be careful not to overwhip the egg whites as they can become dry and grainy. Stop once they reach stiff peaks and have a shiny, smooth texture.
Mix the cream cheese and egg yolks together in a separate bowl before gently folding them into the egg whites. Take care not to deflate the egg whites too much during this step.
To Store: Put some parchment paper between each slice and store in an airtight container in the refrigerator for 3 days.
To Freeze: Wrap individually in plastic wrap and place in a freezer-safe container for 1-2 months. Let it thaw in the fridge before serving.
To Reheat: Warm in an oven or air fryer until heated through. Alternatively, microwave the cloud bread for a few seconds, being careful not to overheat.