Prinsesstårta (Marzipan-Domed Cream Cake)

Variations

• Colour: pale green is standard, but yellow and pink are sold in Sweden too. The pink one has become the breast cancer campaign's rosa bandet-tårta, so the colour now carries a meaning of its own.
• Operatårta: the sibling cake, sheeted in chocolate marzipan with chocolate cream inside. Same construction, different colour and flavour.
• The jam: raspberry is standard and strawberry is common. Seedless is preferred not for texture but because it spreads thinner.
• Where the name came from: it appeared in a 1930s book by the cookery teacher Jenny Åkerström, who taught the three Swedish princesses, and it was originally just grön tårta — green cake. The princesses' fondness for it is the usual explanation for the change. Sweden even has a Prinsesstårta week in late September.
• How it differs from dobos torte: both are layer cakes, but what stacks them and what covers them are opposites. Dobos stacks with buttercream and finishes with a caramel sheet, flat. This stacks with custard and whipped cream and finishes in marzipan, domed. One ends in sugar work, the other in pastry work.
• Against sachertorte: a ganache is a finish you pour and let flow; marzipan is a finish you roll and drape.
• Fondant instead of marzipan: easier to handle and it tastes only of sugar. Marzipan is half almond, so it works as an ingredient rather than a covering — a cousin of the ground almonds in a macaron.
• What it belongs with: if kanelbulle is the everyday coffee bread, this is the birthday cake — the course after Swedish meatballs.

Tips

• Set the cream dome hard before the marzipan goes near it. This is where the cake fails, and the cause is always the cream rather than the marzipan. If a fingertip leaves a dent, it is not ready. Do not shorten the hour, and give it longer in a warm kitchen.
• Roll on icing sugar. Flour dries the surface of marzipan and it cracks, and a crack only opens wider once the sheet is stretched over a dome. Icing sugar dissolves in and leaves no trace.
• Work the diameter out first. You need roughly cake diameter + height × 2 + 4cm of slack. A 22cm cake with a 5cm dome comes to 36cm. Falling short means balling it up and re-rolling, and marzipan gets slightly worse every time you do.
• Lay it down from the centre. Starting at one edge traps air on the far side and puts a fold in it. Landing the middle on the top of the dome and sweeping outwards is the only reliable way.
• Do not over-knead the marzipan. The almond oil comes out and the surface turns greasy and tacky. A drop or two of colouring, and stop the moment it is even.
• Boil the pastry cream a full minute after it thickens. Egg yolks contain amylase, an enzyme that breaks starch down, and without enough heat the cream slackens back to liquid in the fridge on its own. That minute is also when the raw starch taste goes (thickening, cooking eggs).
• Fold the genoise, do not stir it. There is a little baking powder, but the structure is whipped whole egg. Stirring knocks that out — the same principle as dobos torte and pound cake, with whole-egg foam doing the job here.
• Keep the jam thin. Between layers it behaves like a lubricant, and a thick layer lets the top slide as you cut.
• Cold cream, cold bowl. The fat has to be cold to whip firm. Lukewarm cream never reaches the stiffness a dome needs, however long you beat it (dairy and heat).
• Dip the knife in hot water and wipe it between cuts. It stops the marzipan and cream dragging.
• You can make it a day ahead — but not the marzipan. Sponge, pastry cream and the assembly are better done the day before; marzipan left overnight in a fridge takes up moisture and goes tacky.