A slice of Guinness chocolate mousse cake on a white plate topped with a ball of cream

Guinness Chocolate Mousse Cake

This decadent chocolate mousse cake is quick and easy to make for a last minute dessert. The malty notes of the Guinness are a great accompaniment to the dark chocolate and a dollop of cream is a great way to round off a slice before serving. Full method below.
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Olivia Higgs
Mar 17
2 mins
Mar 17
2 mins

Perfect for St Patrick’s day celebrations or for just bringing a taste of Irish flavors into your kitchen. This recipe is inspired by the Chocolate Nemesis cake made famous by London's River Café. It's decadent and gooey, and can be compared to a sliceable chocolate truffle rather than a cake. We found the creamy, coffee and malty notes from the Guinness make the perfect accompaniment to the chocolate. It's a dry stout with a dark colour and characteristic taste that has almost taken on the role as unofficial sponsor of Ireland around the world and as a cooking alcohol, Guinness is used across the Irish kitchen from bread to stews to bakes. This is a rich dessert so a slice goes a long way and is delicious served with a little crème fraîche or sour cream.


  • 5 eggs
  • 285g/10 oz sugar
  • 340g/12 oz dark chocolate (70%)
  • 225g/8 oz unsalted butter
  • 75ml/ 1/3 cup water
  • 50ml/ 1/4 cup Guinness
  • To serve: crème fraîche or sour cream

Prep time: 20 minutes
Cook time: 1 hour

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  • Preheat oven to 130C/250F. Grease and line a 23cm/9 inch cake tin with parchment paper.
  • Break the chocolate into smaller pieces and place into a heatproof bowl with your butter. Melt together over simmering water.
  • Whilst you're waiting for your chocolate and butter to melt we can grab our electric whisk. In a separate bowl whisk your eggs with a third of your sugar until the volume quadruples.
  • Add your remaining two thirds of sugar into a small saucepan along with your water and Guinness. Heat until sugar fully dissolves and you're left with a syrup. Slowly pour your syrup in with your melted chocolate which should be done by now. Allow to cool slightly.
  • Gradually fold your chocolate syrup mixture into your whisked eggs. Pour the mixture into your prepared cake pan.
  • Put your cake tin into a deep baking dish (you can put a dish towel underneath the cake tin to stop it from moving). Fill the baking dish with hot water so it comes 2/3 up the cake tin. Bake for 1.5 hours.
  • To check if the cake is done, place a hand on top - there should be a light crust and it should be slightly firm to the touch. The cake should slightly pull away from the edges, the inside will have firmed up a little but will still be gooey with a mousse-like texture.
  • Once cooked, leave to fully cool down before removing from the tin and slicing. Serve with crème fraîche or sour cream. You can store leftovers in the refrigerator but the cake will stiffen so make sure to bring your portion to room temperature an hour before eating to allow the cake to soften.
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