Cotton Cake

Cotton Cake earns its name honestly. The crumb pulls apart in tender, pillowy tufts thanks to a secret ingredient that throws off most modern bakers: mashed potato. Half a cup folded into the batter holds moisture better than any modern stabilizer, and you cannot taste it.

This is heirloom cake-baking, the kind your great-grandmother knew but the internet half-forgot. The egg whites get whipped separately and folded in last, giving the cake its airy structure. Cocoa powder makes it chocolate. Marshmallow filling between layers and foaming icing on top push it into birthday-cake territory.

The technique is fussy by modern standards. You cream the butter with one portion of sugar, beat the yolks with another, whip the whites with a third, then bring them together in the right order. Skip a step and the cake collapses on itself.

Use cooled, plain mashed potato. No butter, no salt. Warm or seasoned potato will deflate the whites and throw off the flavor.

Pro Tips

• Beat egg whites only to soft-medium peaks, not stiff. They need room to expand in the oven without splitting.
• Fold the whites in three additions. The first lightens the heavy batter; the next two preserve the air.
• Make and refrigerate the mashed potato a day ahead. Cold, dry potato folds in cleanly without lumping.
• Cool the layers fully before applying marshmallow filling. Warm cake melts marshmallow into a puddle.

Variations

• Skip the cocoa for a vanilla cotton cake. The potato magic still works and the crumb stays just as tender.
• Use raspberry jam instead of marshmallow between layers for a tart contrast against the sweet icing.
• Replace foaming icing with a glossy chocolate ganache for a darker, more grown-up finish.