Gâteau de Savoie — the feather-light Savoy sponge

i. Origin & history

The cake is named after Savoy, the Alpine territory now split between south-eastern France and north-western Italy, which was ruled for centuries by the House of Savoy. Its traditional origin story is a court legend. In the version usually told, it was created in the mid-fourteenth century by Pierre de Yenne, cook to Amadeus VI, Count of Savoy — known as the Green Count — for a banquet honouring the Holy Roman Emperor Charles IV. The cake was supposedly baked in the shape of the count's lands, a sweet way of presenting a territory to an emperor.

The date and details are impossible to verify, and the recipe as we know it is clearly later: sponges leavened purely with whipped egg became common in European cookery in the sixteenth and seventeenth centuries. What is certain is that "biscuit de Savoie" was an established name by the eighteenth century, and that the cake became a fixture of French household and pastry-shop baking. Its close relative, the Savoy biscuit or savoiardo, is the finger-shaped sponge known in English as the ladyfinger and in Italy as the base of tiramisu.

The town of Yenne in Savoie still celebrates the cake, and in the region it remains a standard dessert for Sunday lunch, christenings and village fêtes. It is typically baked in a tall, fluted brioche-style or Bundt-like mould, sliced simply and dusted with icing sugar.

It is sometimes confused with génoise, the other foundational French sponge. Génoise is made by whisking whole eggs with sugar over heat and often includes melted butter; gâteau de Savoie separates the eggs, whips the whites on their own and contains no fat beyond the yolks, which makes it lighter, drier and more open-textured.

ii. Why potato starch and separated eggs make it so light

Gâteau de Savoie has no chemical raising agent, so every bubble in the crumb starts as air whipped into the eggs. The yolks are beaten with most of the sugar until pale, thick and almost doubled; the whites are whipped separately into a firm, glossy meringue. Folding the two together gives a very aerated batter, and in the oven that air expands and the egg proteins set around it.

The starch is the other half of the secret. Replacing half the wheat flour with potato starch (fécule de pomme de terre) reduces the amount of gluten in the batter, so the crumb is more tender and less chewy. Potato starch also gelatinises at a relatively low temperature and absorbs a lot of water, which helps the cake set quickly and keep its height without becoming tough. Cornflour does the same job almost as well.

Because the batter is so delicate, folding technique matters more than anything else. The dry ingredients must be sifted over the foam and folded in with a large spatula using broad, slow strokes, just until no streaks remain. Each extra turn of the spatula deflates the batter and costs height.

The mould is prepared like a soufflé dish: buttered and then dusted with sugar or flour. The coating gives the rising batter something to cling to so it climbs evenly, and it gives the finished cake a thin, slightly crisp, golden crust. A moderate oven — around 160 °C — lets the cake rise fully before the crust sets; too hot, and it domes, cracks and sinks.

iii. Ingredients

Makes 10 servings · scroll the side panel to adjust

• 6 large eggs, separated, at room temperature
• 180 g caster sugar
• 75 g plain flour
• 75 g potato starch (or cornflour)
• 1 lemon, finely grated zest
• 1 tsp vanilla extract
• 1 pinch salt
• 15 g soft butter, for the mould
• 1 tbsp caster sugar, for the mould
• 1 tbsp icing sugar, to dust

Potato starch is sold in French and Eastern European grocers and in many supermarkets' baking aisles; it gives the most authentic texture, but cornflour is a good substitute. Use plain flour, not self-raising — there should be no chemical leavening. Room-temperature eggs whip to a larger volume than cold ones. Lemon zest and vanilla are the traditional flavourings; some Savoyard families use orange-flower water or a little kirsch instead. Because there is no butter in the batter, the cake is relatively low in fat, but it relies entirely on the eggs, so use the best you can.

iv. Method

1. Heat the oven to 160 °C (325 °F), fan 145 °C. Brush a 22–24 cm fluted savarin, brioche or Bundt mould (about 2 litres) generously with soft butter, then dust with caster sugar, tapping out the excess.
2. Sift the flour and potato starch together twice.
3. Beat the egg yolks with 130 g of the sugar, the lemon zest and vanilla for 4–5 minutes, until pale, thick and falling from the whisk in a ribbon that holds its shape for a few seconds.
4. In a clean bowl, whisk the egg whites with the salt to soft peaks. Add the remaining 50 g sugar gradually and whisk to firm, glossy peaks that stand up but are not dry.
5. Stir a quarter of the whites into the yolk mixture to loosen it. Sift half the flour mixture over and fold in gently, then fold in half the remaining whites. Repeat with the rest of the flour and whites, folding just until no streaks remain.
6. Pour into the mould, level gently and tap once on the counter to release large air pockets. Bake for 35–40 minutes, until well risen, golden, springy when pressed and a skewer inserted in the centre comes out clean. Do not open the oven in the first 25 minutes.
7. Turn the cake out onto a wire rack after 5 minutes and leave to cool completely. Dust with icing sugar before serving.

v. Tips & common mistakes

• Beat the yolks to a proper ribbon. Under-whipped yolks leave the batter heavy and the cake dense at the base. Give them the full five minutes.
• Do not over-whip the whites. Firm and glossy is right; dry, grainy whites will not fold in smoothly and leave white pockets in the crumb.
• Sift twice, fold gently. Sifting aerates the starch and stops lumps. Fold with a large spatula, cutting through the centre and turning the bowl.
• Prepare the mould thoroughly. Any bare patch will stick, and a fluted mould is unforgiving. Butter and sugar every ridge.
• Keep the oven moderate. At high heat the crust sets before the cake has finished rising, so it cracks and then sinks as it cools.
• Unmould while warm. Left too long in the tin, the cake steams and its crust turns soft and sticky.

vi. Variations

Many Savoyard households add a spoonful of kirsch or orange-flower water, or replace the lemon with orange zest. Some recipes use only potato starch, giving an even more tender, slightly crumbly cake that is also gluten-free. Baked in a round tin, the batter becomes a light sponge that can be split and filled with jam or pastry cream; piped into fingers and dusted with sugar, it becomes biscuits à la cuillère — ladyfingers — the essential sponge for charlottes and tiramisu.

Its closest relatives are the egg-leavened sponges of other cuisines: the Portuguese pão de ló, the Italian pan di Spagna, the Japanese-style roll cake sponge, and the golden sponge. The same whipped-egg principle underlies the rolled sponge of the bûche de Noël, while the Swedish prinsesstårta uses a potato-starch sponge very like this one.

vii. Serving & storage

Gâteau de Savoie is a plain cake by design, served in slices with a dusting of icing sugar. In Savoie it is eaten with coffee or as the dessert after Sunday lunch, often with a fruit compote, red-berry coulis, crème anglaise or a bowl of whipped cream. It is also excellent with poached pears, fresh strawberries or a glass of sweet wine, and its dry, open crumb soaks up sauces beautifully.

Keep the cake wrapped or under a cake dome at room temperature for up to 3 days; it dries out in the fridge. Slightly stale slices can be toasted, used in trifles or soaked in syrup. The cake freezes well for up to two months, well wrapped; thaw at room temperature in its wrapping.

ix. More from French

• Bûche de Noël — Christmas log cake
• Financier — brown-butter almond cake
• Dacquoise — nut meringue layer cake
• Golden Sponge — airy egg sponge
• Prinsesstårta — Swedish princess cake
• Matcha Roll Cake — Japanese roll cake