"Gerbeaud" (Zserbo in Hungarian) is perhaps the best known pastry in Hungary and has a history of 125 years. The slice originated from the legendary Gerbeaud Cafe in the heart of Budapest, Hungary, one of the most traditional and famous cafe-confectioners in Europe. It is baked for celebrations and special occasions such as birthdays and weddings. The word "Gerbeaud" is never translated as it 'understood' that if you order it at the Gerbeaud Cafe you will know what it is. It is made up of thin, tender layers of sweet yeast dough alternating with ground walnuts and rich apricot jam. Rick Rodgers has a fabulous recipe and history of Gerbeaud in his wonderful book - Kaffeehaus: Exquisite Desserts from the Classic Cafés of Vienna, Budapest, and Prague.
This is my mother-in-law's interpretation of the recipe - she doesn't use yeast. Instead she uses half self-raising flour and half plain flour. I have been making it for several years now and it is not as dry as the yeasted version. It is a little fiddly to make but well worth the effort. (The dough doesn't have any sugar as the filling is very sweet).
For the dough:
250g unsalted butter
250g self-raising flour
250g plain (all-purpose flour)
225g sour cream
pinch of salt
1 teaspoon pure vanilla extract or rum.
200g castor sugar
200g ground walnuts*
400g apricot jam**
For the chocolate couverture:
100g Callebaut bittersweet chocolate (70%), finely chopped
1/3 cup castor sugar
1/4 cup water
1 tablespoon unsalted butter
Mix together the butter, sour cream, salt, rum (or vanilla) and flour. Knead for a few minutes until the dough comes together. Divide the dough into three portions. Chill for 20 to 30 minutes to make it firmer and easier to handle.
For the filling, mix the castor sugar, ground walnuts and apricot jam together. Set aside.
Now for the fiddly bit. Roll out each piece of dough to fit a lamington tin (approximately 18cm x 30cm). I draw the shape of the tin on baking paper, roll out each piece of dough to cover the shape, cut around the shape, then transfer to the tin over the back of the rolling pin, pressing the dough into the corners to fit. Alternatively, you can trim the edges neatly to fit the tin as you put it in (but not as easy as the first method).
Using the back of a large spoon, gently spread with half of the filling. The dough underneath has a tendency to move. Just push it back into place as you go. Roll out another layer of dough and fit into the pan, and spread with the remaining layer of filling. Cover with the third layer of dough. Brush the top with water and prick all over with a fork.
Bake for 30 to 40 minutes until the top is golden brown. Let it stand until it cool (over an hour). Cool on a wire rack for 15 minutes, run a sharp knife around the edges to loosen any caramelization. Hold a long rack over the pan and invert to unmold the cake. Leave the cake upside down (smooth side up) and let it cool completely.
For the chocolate couverture (once the cake has cooled) in a small saucepan, bring the chocolate, sugar and water to the boil over medium heat, stirring often. Boil until a sugar thermometer reaches 104°C (220°F), 3 to 4 minutes. Remove from the heat and stir in the butter until it is melted. Cool the chocolate couverture slightly until it just starts to thicken but is still pourable. Work a little faster here as the couverture will start to set. Let it ooze over the edges. Don't be fussy as this is trimmed off later. Refrigerate the cake until the chocolate sets.
When set, using a sharp knife dipped into hot water, trim the edges off neatly and cut into 24 pieces (The remnants are possibly the best bits as the walnuts and apricot jam mix will be caramelized and rich).
*I use vacuum packed walnuts from Australian Organic Walnut Products, so fresh and wonderful. There is no comparison with stale bitter supermarket varieties. I was using walnuts from my mother-in-laws walnut tree but due to the drought here in Victoria, Australia, the walnuts are all tiny and black in side.
**Use the best quality apricot jam you can find - one with the consistency of a jam that your grandmother would have made (lovely and thick and full of fruit).