Kremówka — Polish puff pastry and vanilla custard slice

i. Origin & history

Kremówka belongs to the Central European family of cream slices descended from the French mille-feuille: Austrian Cremeschnitte, Slovenian kremna rezina, Croatian kremšnita and Hungarian krémes. The idea travelled through the pastry shops of the Habsburg lands in the nineteenth century, and each country settled on its own proportions. The Polish version is defined by a deep, set custard — often several centimetres tall — between just two layers of pastry, with no icing on top, only a dusting of sugar.

The name comes from krem, cream, so kremówka is simply 'the cream one'. In many parts of Poland it is also called napoleonka, a name it shares with the French napoleon. Some bakers draw a distinction — a napoleonka with a lighter, creamier filling, a kremówka with a firmer custard — but in practice the two names are used for the same cake.

Its fame comes from Wadowice, the small town near Kraków where Karol Wojtyła, later Pope John Paul II, grew up. During his visit to Wadowice in 1999, he recalled to the crowd how, after the matura (school-leaving) exams, he and his classmates had gone for kremówki at a local pastry shop. The remark was widely reported, Wadowice's cake shops were overwhelmed with orders, and 'papal kremówka' became a fixture for pilgrims and a cake sold all over Poland under that name. Wadowice bakeries still sell it in quantity.

For its Russian many-layered relative, made with eight or more thin pastry rounds, see Napoleon cake.

ii. A custard firm enough to stand up

The challenge of kremówka is the custard. It has to be soft and creamy to eat, but firm enough to stand 4–5 cm tall when cut, without oozing out from between the pastry or collapsing under the top sheet. Ordinary pastry cream is too loose.

Polish bakers solve this with a cooked custard thickened with a mixture of plain flour and potato starch (mąka ziemniaczana), plus plenty of egg yolks. Flour gives body and stability, potato starch a clean, smooth set and a slight wobble, and the yolks richness and colour. The custard must be cooked until it boils and thickens properly — starch only reaches full thickening at boiling point, and under-cooked custard stays soft and can thin out as it stands.

Butter beaten in while the custard is still hot adds richness and helps it set firmer as it chills. Some modern recipes beat in more butter once cooled, giving a richer, mousse-like cream, or add whipped cream for lightness; those versions usually need a little gelatine to hold their shape.

The other key is the order of assembly. The hot custard is poured straight onto the bottom pastry sheet in a lined tin, the top sheet laid on, and the cake chilled for hours. As it cools, the custard bonds with both layers and sets firm, so the slice can be lifted out and cut cleanly. A pre-cut top sheet makes portions neat, since cutting through crisp pastry over soft custard otherwise squashes it.

iii. Ingredients

Makes 12 servings · scroll the side panel to adjust

• 500 g all-butter puff pastry (2 sheets)
• 1000 ml whole milk
• 1 vanilla pod, split, or 2 tsp vanilla extract
• 6 egg yolks
• 200 g caster sugar
• 60 g plain flour
• 60 g potato starch
• 100 g unsalted butter, soft
• 30 g icing sugar, to dust

Use all-butter puff pastry; shop-bought is what most Polish home bakers use. Potato starch is standard in Polish baking and gives the custard its characteristic smooth set; cornflour is the closest substitute. A real vanilla pod gives the best flavour and the speckled look of a bakery kremówka. If you prefer a lighter filling, fold 200 ml of whipped double cream into the cooled custard together with 2 sheets of bloomed gelatine dissolved in a little warm custard.

iv. Method

1. Heat the oven to 200°C (180°C fan, 400°F). Roll each pastry sheet to fit a 24 × 24 cm square tin (or a frame of similar size). Prick them all over and bake on lined trays, each covered with baking paper and a second tray to stop them rising too much, for 15 minutes. Remove the top trays and bake 5–10 minutes more until deep golden and crisp. Cool.
2. Trim both sheets to fit the tin exactly. Cut the better-looking sheet into 12 squares and keep it for the top. Line the tin with baking paper overhanging the sides and lay the other sheet in the base.
3. Heat 800 ml of the milk with the vanilla pod until steaming.
4. Whisk the yolks and sugar until pale, then whisk in the flour, potato starch and remaining 200 ml cold milk until smooth.
5. Remove the vanilla pod, scraping the seeds into the milk. Whisk the yolk mixture into the hot milk and cook over medium heat, whisking constantly and reaching into the corners, until it thickens and bubbles. Keep whisking and let it bubble for 1–2 minutes more.
6. Off the heat, whisk in the butter until glossy. Pour the hot custard straight onto the pastry in the tin and smooth it level.
7. Lay the pre-cut squares of pastry on top, pressing very gently. Cool, then chill for at least 4 hours, ideally overnight.
8. Lift out by the paper, cut down between the top squares with a sharp serrated knife, and dust generously with icing sugar.

v. Tips & common mistakes

• Weight the pastry while it bakes. Unweighted puff pastry rises unevenly into pillows; you want flat, crisp, even sheets.
• Bake the pastry dark. Pale pastry turns soft under the custard within hours. Golden-brown pastry stays crisp longer.
• Boil the custard. It must bubble for a minute or two once thick, or the starch will not set fully and the filling slumps.
• Pour it hot. Hot custard settles level and bonds with the pastry; cooled custard is lumpy to spread.
• Pre-cut the top. Cutting through a whole top sheet squeezes the custard out. Pre-cut squares give the neat bakery look.
• Chill properly. At least 4 hours, so the custard sets firm enough to stand tall when cut.

vi. Variations

Kremówka papieska from Wadowice is the classic custard version. Napoleonka with whipped cream uses a lighter, gelatine-set mixture of custard and cream. Some bakeries add a thin layer of whipped cream over the custard, much like Slovenian kremna rezina; others glaze the top with icing, as for Austrian Cremeschnitte. A shortcut kremówka uses Polish instant custard (budyń) powder.

For a Russian take with many thin layers, see Napoleon cake; for other Polish classics, try sernik, szarlotka and the carnival pastries faworki.

vii. Serving & storage

Serve kremówka cold, one tall square per person, with coffee or tea. It is eaten with a fork — or, more honestly, picked up and bitten from the side, with custard and sugar everywhere. In Polish cafés it is a standard afternoon cake, and in Wadowice a souvenir for visitors.

It is best within 24 hours, while the pastry is still crisp. Keep covered in the fridge for up to 2 days; the pastry softens over time. Kremówka does not freeze well — the custard weeps and the pastry turns soggy. The pastry sheets can be baked a day ahead and kept airtight.

ix. More from Eastern European

• Napoleon Cake — Russian many-layered cake
• Kremna Rezina — Slovenian cream slice
• Cremeschnitte — Austrian custard slice
• Sernik — Polish baked cheesecake
• Faworki — Polish angel wings
• Babka — Polish Easter yeast cake