Preheat and Prep: Preheat your oven to 150°C (fan-assisted). Line a baking tray with parchment paper. The paper should feel crisp and dry when you touch it.

Whip the Egg Whites: In a clean, dry bowl, beat the 4 egg whites with the cream of tartar using a hand mixer on medium speed. After about 3 minutes, the mixture will turn from a clear liquid into a foamy, white mass with small bubbles.

Form Stiff Peaks: Increase the speed to high. The foam will thicken and become glossy. After another 3–4 minutes, lift the beaters — the peaks should stand straight up without flopping over. The bowl should feel stable when tilted.

Fold in the Yolks: In a separate bowl, whisk the 4 egg yolks with the softened cream cheese, salt, and pepper until smooth and pale yellow. Gently fold this mixture into the whipped egg whites using a spatula. Stop as soon as you see no white streaks remaining — overmixing will deflate the air you've created.

Shape and Bake: Spoon the mixture onto the prepared tray into 4 equal rounds, each about 10cm wide. Smooth the tops gently. Bake for 20–22 minutes. The cloud bread will puff up and turn a light golden brown. The surface should feel firm and spring back when lightly pressed. Transfer to a wire cooling rack.

Cook the Turkey Bacon: While the bread bakes, heat the olive oil in a non-stick frying pan over medium heat. Add the turkey bacon slices. Cook for 3–4 minutes per side. You'll hear a gentle sizzle, and the edges will become crispy and deep brown. Transfer to a plate lined with kitchen paper.

Fry the Eggs: In the same pan, crack the 4 filling eggs. Cook sunny-side up for 3–4 minutes until the whites are set and opaque, but the yolks remain runny. The edges should be slightly lacy and golden.

Assemble the Sandwiches: Once the cloud bread is cool to the touch, slice each round horizontally. Spread mayonnaise on the bottom half if using. Layer two slices of turkey bacon, a fried egg, and a sprinkle of cheese and spinach. Top with the other cloud bread half.