Gerbeaud Cake — the layered walnut slice of a Budapest café

i. The café behind the cake

The confectionery that became Gerbeaud was founded in Pest in 1858 by Henrik Kugler, from a family of confectioners, and moved in 1870 to the square now called Vörösmarty tér, at the head of Váci utca. In 1884 Kugler brought in Émile Gerbeaud, a confectioner from Geneva, and Gerbeaud soon took over the business, which came to bear his name.

Gerbeaud turned the shop into one of the grand coffee houses of Austro-Hungarian Budapest. He is remembered for French-trained refinement, for expanding the range to hundreds of cakes, bonbons and ices, and for innovations that are often credited to him, such as the cognac-soaked sour-cherry bonbon (konyakos meggy). The interiors — chandeliers, marble tables, carved wood and stucco — date largely from the turn of the twentieth century and are still the backdrop today. Gerbeaud died in 1919, but the café kept his name until the communist period, when it was nationalised and renamed; it took back the Gerbeaud name in the 1980s and remains one of the city's best-known cafés.

The layered walnut, apricot and chocolate slice is the cake most associated with the house and is sold there as the Gerbeaud szelet. Exactly when it was first made is not well documented, and it is likely that it developed from the nut-and-jam layered pastries already common in Viennese and Hungarian baking; what is clear is that the café gave it its name and its fame. From there it moved into home kitchens across the country, where it is written zserbó — the way Hungarians spell the French name — and baked as a Christmas and celebration slice; that home-style version, with a soft yeasted dough, has its own page at zserbó szelet.

So the names map simply: Gerbeaud cake or Gerbeaud slice is the usual English and café name, zserbó szelet the everyday Hungarian one. Visitors to Budapest generally meet it first on the café's cake counter, often alongside somlói galuska and Dobos torte.

ii. Thin layers and a glaze that cuts cleanly

A patisserie Gerbeaud slice is defined by precision: very thin, even layers in fine proportion, and a smooth chocolate top sharp enough to show clean edges when the slab is cut into neat rectangles. Getting there is mostly about the dough and the glaze.

The pastry here is a rich short dough leavened with a little baking powder rather than yeast. It bakes slightly crisper and more uniform than the soft yeasted home dough, which suits four thin sheets and gives the slice a more defined, almost striped cross-section. The baking powder keeps each sheet from becoming hard or biscuity as it bakes, but because the sheets are only 2–3 mm thick there is no real rise. Rolling them to the exact size of the tin between sheets of baking paper is what keeps the layers level.

Moisture is the hidden ingredient. Thin jam layers on both sides of a pastry sheet soften it gradually; a day's rest under a light weight lets the jam migrate into the pastry and the walnut layer absorb the excess, so the layers bond into a single tender slab. Cut immediately, the same cake crumbles and the layers slide apart.

The glaze is a simple chocolate ganache-like mix of dark chocolate, butter and a little cream with a spoon of sugar syrup or honey for gloss. Pure melted chocolate sets hard and brittle and shatters under the knife; the added fat and liquid keep it soft enough to cut cleanly while still setting firm and shiny at room temperature. A hot, dry knife, wiped between every cut, gives the café-style edge.

iii. Ingredients

Makes 30 servings · scroll the side panel to adjust

• 500 g plain flour
• 275 g unsalted butter, cold
• 80 g icing sugar
• 1 tsp baking powder
• ¼ tsp salt
• 2 egg yolks
• 100 g sour cream
• 300 g walnuts, finely ground
• 160 g caster sugar
• 1 tsp vanilla extract
• 450 g apricot jam, smooth
• 180 g dark chocolate (60–70%)
• 50 g unsalted butter (glaze)
• 60 ml double cream
• 1 tbsp honey or golden syrup

A smooth, tart apricot jam is essential — sieve it if it has chunks, so it spreads in thin, even films. The walnuts are mixed with sugar and vanilla and scattered dry; grind them fine but stop before they turn oily. Egg yolks and sour cream make the dough short and tender, and the baking powder stops thin sheets baking hard. For the glaze, cream, butter and honey are what keep the chocolate glossy and sliceable; use chocolate you would eat on its own. If you prefer a softer home-style pastry, the yeasted dough on the zserbó szelet page works with these fillings.

iv. Method

1. Whisk the flour, icing sugar, baking powder and salt. Rub in the cold butter until no large lumps remain, then add the yolks and sour cream and bring together into a smooth dough. Divide into four equal pieces, flatten into rectangles, wrap and chill for 1 hour.
2. Heat the oven to 180°C (160°C fan, 350°F). Line a 25 × 35 cm tin with baking paper. Mix the walnuts, caster sugar and vanilla. Warm the jam gently until spreadable.
3. Roll each piece of dough between two sheets of baking paper to the exact size of the tin, 2–3 mm thick. Keep the rolled sheets chilled on trays.
4. Lay the first sheet in the tin, prick it all over and bake for 8–10 minutes until set but still pale. Let it cool for a few minutes.
5. Spread a third of the jam over the base and scatter a third of the walnut mixture evenly. Lay the second sheet on top and press lightly. Repeat twice more, finishing with the fourth sheet. Prick the top all over with a fork.
6. Bake for 35–40 minutes until the top is pale golden and a skewer meets no raw dough. Cool completely in the tin.
7. Cover with baking paper, set a board and a light weight (about 1 kg) on top and leave for 12–24 hours at cool room temperature.
8. For the glaze, bring the cream and honey to a simmer, pour over the chopped chocolate and butter, wait 2 minutes, then stir until smooth and glossy. Pour over the slab, smooth with a palette knife and leave until set, about 2 hours.
9. Trim the edges and cut into neat 4 × 6 cm rectangles with a long knife dipped in hot water and wiped dry between every cut.

v. Tips & common mistakes

• Weigh the dough into four. Equal portions give equal layers; the striped cross-section is half the look of a café slice.
• Keep rolled sheets cold. This dough softens fast. Cold sheets transfer onto the filling without tearing or stretching out of shape.
• Use thin, sieved jam. Lumpy or thickly spread jam makes uneven layers and weeps at the edges. Warm it just enough to spread.
• Scatter the walnuts, do not press them in. A loose, even layer lets the next pastry sheet sit flat and absorbs moisture from the jam.
• Weight it overnight. The rest under a board compacts the layers and is the difference between a neat café slice and a crumbly one.
• Trim the edges before cutting. The outer centimetre is drier and uneven; trimming it is what gives professional-looking pieces (and a baker's snack).

vi. Variations

The home zserbó uses a soft yeasted dough in three layers and is usually cut into small squares for Christmas plates — see zserbó szelet. Some bakers use raspberry or plum jam, add raisins or cocoa to the nut filling, or replace the walnuts with hazelnuts. A plainer finish uses a cooked cocoa and sugar icing in place of ganache.

Gerbeaud cake sits in the Austro-Hungarian family of layered pastries and nut-and-jam bakes: compare the Austrian Linzer torte, the Viennese meringue-sponge Kardinalschnitten, the Slovenian cream slice kremna rezina and the many-layered Russian honey cake medovik.

vii. Serving & storage

Serve Gerbeaud cake as the café does: a single neat rectangle on a small plate at room temperature, with an espresso, a melange (milky coffee) or tea. It is rich and needs no cream. Cut smaller, it makes an excellent part of a Christmas or party platter.

The slab keeps for a week in an airtight container at cool room temperature and is at its best on the second and third days. Refrigerate only in a warm kitchen, and bring slices back to room temperature so the pastry and glaze soften. It freezes well for up to two months: freeze uncut or in pieces, wrapped tightly, and thaw overnight in the fridge before bringing to room temperature.

ix. More from Eastern European

• Zserbó Szelet — the home-baked Hungarian slice
• Somlói Galuska — Hungarian sponge and rum trifle
• Mákos Guba — Hungarian poppy-seed bread pudding
• Kremna Rezina — Slovenian cream slice
• Kardinalschnitten — Viennese meringue slices
• Linzer Torte — Austrian nut and jam tart