Chocolate, hazelnut and caramel traybake

Start by making the chocolate sponge. Preheat the oven to 170°C fan, then line a 20 x 30cm baking tray with parchment paper

In a stand mixer fitted with a whisk attachment, cream together the butter and caster sugar until light and fluffy. Whisk through the vanilla bean paste then add in the eggs one at a time

Mix in the flour, cocoa powder and milk, then whisk on a medium speed until the batter is smooth

Transfer to the lined baking tray and bake for around 30 minutes until cooked through. Leave to cool for around 10 minutes before turning out of the baking tray onto a wire rack to finish cooling

Meanwhile, make the caramel. In a separate pan, make the caramel. Bring the water and sugar to a simmer in a heavy-bottomed, high-sided pan, and swirl the pan to dissolve the sugar

Cook until you have a light caramel, swirling occasionally. The sugar should be around 170°C

Remove from the heat and – very carefully – add in the butter and cream and stir with a spoon until melted and mixed through

Once the sauce is smooth, set aside to cool

Next, finish the caramel buttercream. To a stand mixer fitted with a whisk attachment, beat the softened butter, then add in the icing sugar in stages. Once the butter and sugar are fully incorporated, add in the caramel sauce and beat until smooth on a medium high speed

To assemble the cake, use a palette knife to spread the caramel buttercream over the top of the cooled sponge. Top with milk chocolate curls