Ingredients

Step by step

1. Preheat the oven to 170°C, fan 150°C, gas 3. Tip the hazelnuts into a small baking tin and toast in the oven for 6-8 minutes until golden brown. Set aside to cool.
2. Grease and base-line a 23cm springform cake tin and dust the sides with the cocoa powder. Shake off any excess and set the tin aside.
3. Gently melt the butter and caster sugar in a pan, stirring until the sugar has dissolved. Remove from the heat, add the chocolate and set aside for 5 minutes to melt. Stir until smooth, pour into a mixing bowl and allow to cool for 10 minutes.
4. Whiz 50g of the cooled hazelnuts to a fine powder with the muscovado sugar in a mini processor. Beat the egg yolks into the melted chocolate mixture, one by one, then when fully combined, stir in the vanilla extract, ground hazelnut mixture and the salt.
5. In a clean, dry bowl, whisk the egg whites to stiff peaks. Stir a spoonful into the chocolate mixture to loosen, then gently fold in the rest with a large metal spoon until incorporated. Carefully pour the mixture into the tin and place the tin on a baking sheet. Slide into the oven and bake for 50 minutes or until risen and feeling set and almost firm in the centre, but still with a slight wobble to it. If you poke the middle with a skewer, it should come out almost clean – we like it a little underdone. Leave to cool in the tin for 10-15 minutes, then release the sides and sit on a wire rack, still on the base, until cooled.
6. While the cake cools, make a hazelnut praline to decorate; tip the sugar into a pan (light-coloured, if possible, to make the colour change more obvious). Heat gently until the sugar melts – don’t stir, just shake the pan. Once all the sugar has melted, increase the heat and cook until you have a golden-brown caramel. Meanwhile, roughly chop the remaining hazelnuts (not too rough, not too small), and line a baking tray with baking paper. When the caramel is ready, remove from the heat and tip in most of the hazelnuts, plus a pinch of sea salt. Immediately pour the hazelnut praline onto the prepared tray and leave to set until solid.
7. Just before serving, whip the cream to just under soft peaks with the liqueur, if using, and the icing sugar. Carefully transfer the soufflé cake to a serving plate and spread with the Nutella, if using. Spoon large dollops of cream onto the cake, then swirl with the back of a spoon or small spatula. Now drizzle with the salted caramel (gently warm in the microwave or in a small pan for easier drizzling). Break up the hazelnut praline into chunky shards and use to decorate the top of the cake. Scatter with the last of the toasted hazelnuts.