Let them have cake: pastries have been a defining feature of Viennese culture for centuries. To mark the 40th anniversary of the IMP, the institute celebrated with a very special cake – the Birnstiel Torte, created in honour of Max Birnstiel, the IMP’s founding director.
Vienna - city of coffee houses and sumptuous pastries! With the Birnstiel Torte, the IMP has created its own signature cake, a sweet symbol of the institute’s history and identity. Pastries are part of Vienna’s culinary heritage since Mary of Burgundy married Emperor Maximilian I. in 1477, allegedly introducing fancy sweet cuisine to Central Europe. Indeed, the IMP has had professional pâtissiers among its cafeteria colleagues for many years – and the Birnstiel Torte is an in-house creation by Monika Lechner, the current holder of this vital post.
The Birnstiel Torte pays homage to Max Birnstiel’s remarkable life and legacy, drawing inspiration from the places that shaped him: Brazil, Switzerland, Scotland, and Vienna. Born in Bahia, Brazil in 1933, Max Birnstiel moved to Switzerland at the age of five, where he was educated and earned his doctorate at ETH Zurich. His scientific journey took him to Edinburgh, where he spent nearly a decade at the University of Edinburgh, isolating the first single gene, a landmark achievement. In 1986, he came to Vienna to shape and lead the newly established IMP, laying the foundations for what would become the Vienna BioCenter.
The flavours of the Birnstiel Torte mirror this international journey – a blend of traditions and tastes from each of these places, crafted into one harmonious whole. The cake combines Swiss chocolate and locally sourced, Austrian pears ("Birnstiel" meaning “pear stem" in German) with a touch of Scotch whisky and Brazilian honey, evoking both refinement and warmth.
Its layers are built on a delicate sponge base of butter, sugar, eggs, flour, and dark couverture chocolate. The ganache cream blends white and dark chocolate with cream and whisky, complemented by pears and pear juice for a bright, fruity note. Finished with a silky chocolate and cream topping and with a glaze of honey –and dark chocolate, the result is a dessert that is both complexly layered and simply delicious.
The first Birnstiel Torte to be made was presented during the IMP’s 40th anniversary symposium on 5 November 2025. A moment of reflection, gratitude, and joy, honouring the visionary whose ideas helped shape four decades of world-class molecular biology in Vienna. As well as the pastry pros at the IMP’s cafeteria.
Birnstiel Torte - the recipie
While the recipes of other legendary Viennese cakes are jealously guarded secrets, the IMP is fully transparent about its signature pastry. Below, you find Monika Lechner's original recipe for you to give it a try.
Chocolate Sponge Base
- 240 g softened butter
- 120 g powdered sugar
- 8 g (1 sachet) vanilla sugar
- 11 eggs
- 240 g dark Swiss chocolate, melted
- 260 g granulated sugar
- 240 g flour, sifted
Preheat the oven to 175°C.
Beat the butter, powdered sugar, and vanilla sugar together until light and fluffy. Separate the eggs and add the yolks to the batter one at a time, mixing well after each addition.
Melt the chocolate in a double boiler and stir it into the batter.
In a separate bowl, beat the egg whites with the granulated sugar until stiff peaks form. Gently fold the beaten egg whites into the batter.
Pour the batter into a 24 cm springform pan and bake at 175°C for about 40 minutes. Allow to cool completely, then remove from the pan.
Pears
- 300 g Austrian pears, cut into small cubes (canned pears are fine if not in season)
- 150 ml pear juice
Mix the pear cubes with the pear juice and set aside.
Chocolate Cream
- 250 ml cream
- 60 g dark chocolate
Bring the cream just to a boil, then remove from the heat. Add the chocolate and blend with a hand blender for about 1 minute, until smooth.
Refrigerate overnight, then whip it the next day as you would whipping cream, until it holds soft peaks.
Whisky Ganache
- 200 ml cream
- 350 g white chocolate
- 100 g dark chocolate
- 90 g butter
- 100 ml Scottish whisky
Bring the cream just to a boil, then remove from the heat. Add the butter, white chocolate, and dark chocolate and stir until completely melted and smooth. Add the whisky and mix again until fully combined. Let cool to a spreadable consistency.
Glaze
- 110 g dark chocolate
- 90 ml cream
- 20 g Brazilian honey
Bring the cream just to a boil, then remove from the heat. Add the chocolate and honey and stir until smooth and glossy. Allow to cool until lukewarm before using.
Bringing It All Together
- Blackberry jam
Slice the chocolate sponge horizontally into two even layers. Place the bottom layer back into the cleaned springform ring.
Spread a thin layer of blackberry jam over the sponge. Using a piping bag, pipe the whisky ganache in a loose spiral over the jam, leaving small gaps here and there. Fill these gaps with the pear-and-juice mixture.
Place the second sponge layer on top and press down gently but firmly. Spread the whipped chocolate cream evenly over the top and sides (if desired), then refrigerate for at least 3 hours, or until well set.
Whisk the chocolate glaze until smooth. When it is lukewarm and pourable, pour it over the torte to cover the top (and sides, if not already covered with cream). Let the glaze set, then decorate as desired.