Baumkuchen

The flour trio does three different jobs, so don't swap one for a bigger pile of another. Plain flour gives structure — gluten, basically, enough to hold the layers together without turning chewy. Potato starch is there to cut that gluten, keeping the crumb fine and slightly short rather than bready; cornflour will do the same job if that's what's in the cupboard, the criterion is "a starch with no flavour of its own and no protein to toughen things." Almond flour adds fat and a faint sweetness and keeps the whole thing from drying out over twenty rounds under a hot grill — ground almonds from the baking aisle work exactly the same way, just sift out any coarse bits.

Butter and sugar creamed together isn't decoration, it's the rise. Cold butter beaten with sugar traps air in tiny pockets; that air is what lifts the cake along with the whisked whites, since this batter has no other raising beyond 2g of baking powder, which is really just insurance, not the main engine. If your butter's too soft or half-melted, the pockets collapse before they're made and you'll get a denser layer — so cold, cubed butter, beaten until it goes pale and fluffy, is doing real mechanical work, not just following tradition.

The egg whites, whisked separately to stiff peaks and folded in with upward strokes, are the other half of that lift — and here's where people lose it. Some say a trace of yolk in the whites doesn't matter — no, because fat coats the protein strands and stops them from forming the web that holds air; one drop of yolk and your peaks go soft and you lose the layer's lightness. A clean, dry bowl isn't fussiness, it's the one condition that makes the whisking work at all.

Dark chocolate and cream poured over it hot is a ganache, and the ratio here — roughly equal weight of each — gives you a glaze that sets to a firm, snappable shell rather than staying soft, because cream this heavy is mostly fat and water in balance with the chocolate's cocoa butter; too little cream and it seizes grainy, too much and it never sets at room temperature, only in the fridge, which is exactly why the recipe sends it to chill. Any dark chocolate with a reasonable cocoa percentage will do — you're not after a prestige bar, you're after something that sets hard enough to crack under a knife.

The apricot jam under the glaze isn't flavour, mainly — it's a seal. Warmed until runny and brushed over the cooled cake, it fills the tiny pores on the surface so the chocolate glazes evenly instead of sinking in patches and looking blotchy; any smooth, not-too-chunky jam does the same job, apricot just has a flavour that doesn't fight the chocolate.

On patience: this isn't a cake you bake and walk away from. It's a cake you babysit, spoonful by spoonful, for the better part of two hours, and that time is the actual ingredient that makes the rings — there's no shortcut that gives you the pattern without the standing-and-watching. Six people, one 22cm cake, cut thin because it's rich and the rings deserve to be seen, not gulped. With tea and milk after, if that's how your Sunday runs.