Bløtkake — Norway's cream-and-strawberry celebration cake

i. Origin & history

Bløt means soft or soaked in Norwegian, and the name describes exactly what sets this cake apart from a plain sponge: the layers are deliberately moistened, so the cake is tender and almost spoonable inside. Cream-filled layer cakes built on a light sponge spread through Scandinavia in the late nineteenth and early twentieth centuries, as baking powder, white flour and reliable ovens reached ordinary homes, and the Norwegian bløtkake became the most familiar of them.

It is a cake strongly tied to occasions. Norwegian birthday parties, christenings, confirmations and weddings almost always have one, and on 17 May — syttende mai, the national day celebrating the 1814 constitution — bløtkake is the expected cake after the children's parades. On that day it is often decorated in the colours of the flag, with red strawberries and blue blueberries on white cream. Supermarkets sell ready-baked sponge bases, bløtkakebunner, in stacks, which tells you how often Norwegians make it.

Every family has its own filling preferences, and they are the subject of genuine debate: vanilla custard or not, jam or fresh berries, juice or milk for soaking, and whether the top should be cream or a lid of marzipan. The marzipan-covered version, marsipankake, is often seen as the more formal cake for weddings and big birthdays, while the cream-topped strawberry bløtkake is the everyday celebration cake.

Denmark and Sweden have very close relatives — the Danish lagkage and the Swedish gräddtårta, whose most famous form is the marzipan-domed prinsesstårta. The German Erdbeer-Sahnetorte and the Japanese strawberry shortcake follow the same idea. The Norwegian bløtkake is distinguished by its moist, soaked layers and its generous, unfussy cream finish.

ii. Why the sponge is fatless and the layers soaked

A bløtkake sponge (sukkerbrød) contains no butter at all. Its structure comes from eggs and sugar whisked for a long time into a thick, pale foam, with flour — often part potato starch — folded in just enough to set it. Without fat, the baked sponge is light, springy and quite dry, which sounds like a flaw but is exactly what a layered cream cake needs: a dry, open crumb absorbs liquid like a sponge, whereas a butter cake would turn heavy and greasy when soaked.

The soaking is what gives the cake its name. Each layer is drizzled with milk, juice or a mixture, a few spoonfuls at a time, so the crumb softens and becomes moist and tender. The amount matters: enough to soften, not so much that the bottom layer becomes a puddle. A little sugar or vanilla in the milk adds flavour.

Potato starch is a characteristically Scandinavian addition to the flour. It contains no gluten-forming protein, so replacing part of the flour with it gives a finer, more tender, slightly melting crumb. Many Norwegian recipes use roughly two parts flour to one part potato starch.

Time does the rest. A bløtkake is best assembled several hours, or even a day, before serving, so the moisture from the soaking, custard and cream migrates into the sponge and the layers settle into a single soft, sliceable cake. Assembled and served immediately, it tastes of separate components rather than a unified whole.

iii. Ingredients

Makes 12 servings · scroll the side panel to adjust

• 5 eggs, at room temperature
• 180 g caster sugar
• 120 g plain flour
• 60 g potato starch
• 1 tsp baking powder
• 300 ml whole milk, for the custard
• 3 egg yolks, for the custard
• 50 g sugar, for the custard
• 25 g cornflour, for the custard
• 2 tsp vanilla extract or vanilla sugar
• 150 ml milk or orange or apple juice, for soaking
• 600 ml whipping cream
• 2 tbsp icing sugar
• 600 g fresh strawberries
• 100 g strawberry or raspberry jam, optional

Potato starch gives the classic fine, tender crumb; replace it with cornflour if necessary or use all flour for a slightly firmer sponge. Room-temperature eggs whisk to a much greater volume than cold ones, and volume is everything. For soaking, milk is the most common choice, sometimes with a little sugar and vanilla; juice or diluted saft (fruit cordial) gives a fresher, fruitier cake. Whipping cream (about 35–38 per cent fat) is what Norwegians use; double cream is fine but whip it carefully. Choose ripe, fragrant Norwegian-style strawberries — small and sweet if you can find them. A layer of jam is optional but common.

iv. Method

1. Make the custard: heat the milk until steaming. Whisk the yolks, sugar and cornflour, pour on the hot milk while whisking, return to the pan and cook, stirring, until thick and bubbling, about 2 minutes. Stir in half the vanilla, cover the surface and chill completely.
2. Heat the oven to 175 °C (350 °F), or 155 °C fan. Grease and line the base of a 24 cm springform tin; do not grease the sides.
3. Whisk the eggs and sugar with an electric mixer for 8–10 minutes until very pale, thick and at least tripled; the foam should hold a ribbon for several seconds.
4. Sift together the flour, potato starch and baking powder, then sift over the foam in three additions, folding gently with a spatula until no streaks remain.
5. Pour into the tin and bake on a low shelf for 35–40 minutes, without opening the door for the first 25, until golden, risen and springy, and a skewer comes out clean. Cool completely in the tin, then release and cut horizontally into 3 even layers.
6. Whip the cream with the icing sugar and remaining vanilla to soft, spreadable peaks. Slice half the strawberries; keep the best whole ones for the top.
7. Place the bottom layer on a plate and drizzle with a third of the soaking milk or juice. Spread with jam, if using, then half the custard, a layer of sliced strawberries and a thin layer of cream. Repeat with the second layer.
8. Add the top layer, drizzle with the remaining soaking liquid, and cover the top and sides with the rest of the cream. Decorate with whole and halved strawberries. Chill for at least 3 hours, or overnight, before serving.

v. Tips & common mistakes

• Whisk the eggs until they truly triple. A fatless sponge has no other source of lift; under-whisked eggs give a flat, rubbery cake.
• Do not grease the sides of the tin. The batter needs to cling to the sides as it rises. Release it with a knife once cool.
• Bake a day ahead. A day-old sponge is firmer and slices into even layers more easily than a fresh one.
• Soak lightly and evenly. Too much liquid makes the bottom layer collapse. Spoon it over gradually and stop when the surface looks damp but not wet.
• Do not overwhip the cream. Cream that is too stiff turns grainy when spread; stop at soft, smooth peaks.
• Give it time to settle. At least 3 hours in the fridge lets the layers absorb moisture and meld into a soft, unified cake.

vi. Variations

Marsipankake covers the cream-filled bløtkake with a thin sheet of marzipan, often pale green or white and decorated with marzipan roses — a classic for confirmations and weddings. Sjokoladebløtkake uses a cocoa sponge with chocolate cream. 17 mai bløtkake is decorated with strawberries and blueberries in the pattern of the Norwegian flag. Some families use tinned peaches or pineapple instead of berries, or multekrem (cloudberry cream) for special occasions.

For other Nordic celebration cakes, see the Norwegian almond-and-custard suksessterte, the Swedish prinsesstårta, and the Danish drømmekage. Similar cream-and-berry layer cakes elsewhere include the strawberry shortcake and the German Black Forest gateau.

vii. Serving & storage

Serve bløtkake chilled, cut into generous wedges with a long, sharp knife wiped clean between slices. It is served with coffee in the afternoon at birthdays and family gatherings and as the dessert at festive meals, especially on 17 May. Lemonade or juice for children and coffee for adults are the usual companions.

Store it covered in the fridge and eat within 2 days; after that the cream starts to weep and the strawberries soften. The unfilled sponge keeps for 2 days wrapped at room temperature, or 3 months frozen, which makes it easy to prepare in stages. The finished cake does not freeze well because of the fresh fruit and custard.

ix. More from Scandinavian

• Prinsesstårta — Swedish princess cake
• Suksessterte — Norwegian success cake
• Skolebrød — Norwegian custard school buns
• Drømmekage — Danish coconut dream cake
• Strawberry Shortcake — strawberry sponge
• Medovik — Russian honey cake