Easy Cloud Cake

Easy Cloud Cake belongs to the family of foam cakes—delicate, whipped-egg desserts where the structural rise relies entirely on air trapped in beaten egg whites rather than heavy butter or chemical leaveners.

Light, pillowy, and melt-in-your-mouth soft, this cake offers a subtle sweetness that pairs beautifully with fresh berries, a dusting of powdered sugar, or a dollop of whipped cream.

Ingredients & Equipment

The Core Sponge Ingredients

Large eggs: 6 pieces, carefully separated (room temperature)
Granulated sugar: ½ cup (100g), divided into two equal portions
All-purpose flour: ½ cup (60g), sifted
Cream of tartar: ¼ teaspoon (stabilizes egg-white foam)
Pure vanilla extract: ½ teaspoon
Fine sea salt: A pinch

Equipment

9-inch round cake pan (strictly ungreased)
Sieve or flour sifter
Electric hand mixer or stand mixer
Silicone spatula
Wire cooling rack

The Food Science of Protein Foam Stabilization

Albumin Denaturation & Foam Formation: Beating egg whites (ovalbumin) untangles tightly coiled protein chains, creating a lattice network that traps air bubbles. The addition of cream of tartar (an acid) lowers the pH, stabilizing the protein bonds so they don’t over-coagulate and collapse during initial baking.
The Ungreased Pan Principle: Foam cakes expand by “climbing” up the interior walls of the baking vessel. Greasing the cake pan creates a slick barrier that prevents the delicate batter from gripping the sides, causing the cake to collapse inward and remain dense.
Inverted Cooling Mechanics: When removed from the oven, the hot air pockets within the protein matrix begin to cool and contract. Cooling the pan inverted (upside down) allows gravity to stretch the delicate egg-protein walls while they set, preventing the sponge from shrinking or sinking in the center.