This is such a beautiful and delicious cake, you get a silky vanilla airy buttercream, crunchy caramel hazelnuts that make it look really beautiful and of course praline folded inside the cake with the buttercream.
I tried to make a little design on the cake with a different coloured sponge but I rolled the cake up (when you roll it to let it cool in the roll shape) on the wrong side, so the design ended up on the inside! Anyway, That's why on the pictures you can see a slightly browner sponge on the inside of the roll.
Before and after the first slice...
Ingredients
For the sponge:
4 eggs, separated
125g caster sugar
150g unsalted butter
150g self-raising flour, sifted
1/2 teaspoon of baking powder
1/4 teaspoon of salt
1 teaspoon of vanilla extract
For the white chocolate gianduja:
50 g hazelnuts
30 g almonds
50 g white chocolate
1/4 teaspoon of salt if needed
For the swiss buttercream:
2 egg whites
100 g caster sugar
140 g butter, super soft
1 teaspoon of vanilla extract
For the candied hazelnuts:
50 g white sugar
around 20 roasted hazelnuts
Recipe
For the sponge:
Pre-heat the oven to 160C and grease + line a swiss roll tin.
Cream the butter + sugar + vanilla together until pale. Then add in the egg yolks and mix until combined and sift in the flour + baking powder and mix slowly until combined.
In a separate bowl, whip the egg whites with the salt until stiff and then fold them into the mixture.
Pour the batter into the prepared baking tray, level off, tap on the counter tor remove air bubbles at the surface, and bake in the preheated oven for 17-20 minutes, until golden and springy to the touch.
Tip onto and piece of parchment paper dusted lightly with icing sugar. Roll lengthways, both sides of the cake in parchment paper, rolling tightly and leave to cool in this log position.
For the praline:
Toast the almonds + 50 g of hazelnuts + 20 hazelnuts in a 150 C oven for about 10 minutes, until golden on the inside and the shells are coming off of the hazelnuts.
Separate the almonds from the hazelnuts and place the hazelnuts into a tea towel. Rub the hazelnuts against each other in the tea towel until their shells come off of them, this takes a little time but it's super important they don't have their shells.
Keep 20 hazelnuts to the side and pulse the rest with the almonds in a food processor until the nuts start sticking to the sides of the food processor.
Add in the melted white chocolate with a tiny bit of salt if it's needed.
Mix until super smooth and keep to the side.
For the swiss buttercream:
In a bain-marie, whisk the egg whites with the sugar with an electric mixer until soft peaks form and all the sugar granules are dissolved. Then place in the bowl of a stand mixer or remove from the heat.
Whisk until the mixture has cooled down and forms stiff peaks.
Add-in, a teaspoon at a time, the super-soft butter, this will take about 5 minutes until the mixture is completely smooth and fluffy. Beat for a further 2 minutes to whip it a little more until the colour is completely white and then mix in the vanilla extract.
For the candied hazelnuts:
Melt the sugar in a saucepan over very low heat, until completely dissolved and amber colour.
Remove from the heat and leave to cool 30 seconds and poke wooden cocktail sticks into the skinless 20 hazelnuts you saved, being careful not to break them!
Dip and swirl the hazelnuts in the caramel, coating them all over in the caramel. Lift up and let the caramel drip until it stiffens a little and is dripping steadily but slowly and secure the wooden cocktail stick onto the counter, letting the excess caramel from the hazelnut drip onto the floor and harden. Repeat for remaining hazelnuts, if the caramel hardens too much, re-heat a little.
Once cool, if the caramel spikes are a little long, cut them to the desired length.
To assemble:
Unroll the cake log and spread half of the buttercream on it.
Spoon on the praline and spread a little to even out.
Roll carefully the cake lengthways into a log.
Place the remaining buttercream into a piping bag and cut off the tip in a nearly straight angle to make a St Honor tip.
Pipe in a swirling motion like on the picture the buttercream onto the middle of the cake roll.
Add on the caramelised hazelnuts and serve.
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Check out the new Baking Glossary on the blog if you are unsure of any baking terms.
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