Image & recipe taken from the BBC
Makes 1 large cake
For the caramel buttercream
800g (1lb 12oz) granulated sugar
100ml (3½fl oz) water
400ml (14fl oz) double cream
450g (1lb) unsalted butter, softened
For the sponge layers
8 large free-range eggs
350g (12oz) caster sugar
300g (10½oz) sifted self-raising flour
For the almond praline and caramel-coated hazelnuts
75g (2¾oz) flaked almonds
16 blanched (skinned) hazelnuts
300g (10½oz) granulated sugar
For the caramel topping
100g (3½oz) granulated sugar
First make the caramel buttercream to cover the cake. Put the sugar and water in a large saucepan. Bring to the boil over medium heat, stirring until the sugar has dissolved.
Once there is no grittiness left, turn up the heat and boil to a golden caramel. Take off the heat, add the cream and give it a quick stir, then pour into a bowl. Leave to cool, then chill until set.
Put the soft butter in the bowl of a free-standing electric mixer and whisk until light and fluffy. Add the cooled caramel mixture a spoonful at a time, whisking between each addition and scraping down the bowl regularly. Keep in the fridge until ready to use.
Heat your oven to 200°C/fan 180°C/gas 6. Draw 6 x 20cm (8in) circles and 6 x 15cm (6in) circles on sheets of baking paper cut to fit a flat baking tray or trays (you’ll probably need to bake the sponges in batches).
To make the sponge layers, break the eggs into a large bowl, add the sugar and whisk until the mixture is foamy and the whisk just leaves a trail when lifted out. Lightly fold in the flour, a little at a time. Divide the mixture among the 12 circles on the baking paper, spreading it out evenly. Bake in batches on the trays in the heated oven for 8-10 minutes until pale golden and springy to the touch. Remove from the oven and set on a heatproof surface. With a sharp knife, trim the sponge to neaten it, then peel off the parchment and leave to cool on a wire rack.
Now make the almond praline and caramel-coated hazelnuts. Spread the flaked almonds over a silicone mat or sheet of baking paper on the worktop. Stick a wooden cocktail stick into each of the 16 hazelnuts. Have ready an orange or piece of foam on the worktop.
Dissolve the sugar in the water in a small pan over low heat, then increase the heat and boil the syrup until it turns a deep golden colour. Allow the caramel to cool slightly, then pour three-quarters of it over the flaked almonds to make the praline. Dip the hazelnuts in the remaining caramel, twisting the sticks so they are coated. Invert and push the sticks into the orange or foam. Leave to cool and set.
Take one of the 15cm sponge layers and place it on a sheet of baking paper, ready to be topped with caramel. To make this, dissolve the sugar in the water in a small pan over low heat, then increase the heat and boil until it turns a deep golden colour.
Allow to cool slightly, then pour it over the sponge layer to cover. When the caramel is just beginning to set, mark it and then cut into 8 wedges using an oiled knife. These will be used for the top layer of the cake.
Sandwich the 20cm sponges with some of the caramel buttercream. Spread buttercream over the top and side of this cake stack. Sandwich the remaining 5 x 15cm sponges with buttercream. Spread it around the side and top of the stack, then place it on top of the 20cm cake stack to form a second tier. Spoon the remaining buttercream into a piping bag fitted with a medium star nozzle.
Break the almond praline into small pieces and press into the side of both tiers of the cake. Remove the caramel-coated hazelnuts from the cocktail sticks. Pipe 16 rosettes of buttercream around the top edge of the 20cm cake. Top each rosette with a hazelnut. Pipe 8 buttercream rosettes on top of the 15cm cake.
Place a caramel-topped wedge of cake at an angle leaning against each rosette to form the top layer. This is best eaten on the day, but it can be chilled for up to 3 days – however, the caramel will melt when kept in the fridge.