finely grated zest 1/2 large lemon plus 3 tbsp juice
150g caster sugar
1 tbsp butter
pinch sea salt
50g (2oz) hazelnuts, toasted and roughly chopped, to decorate
extra orange zest, to decorate
Place one slice of panettone on a serving platter and slice the panettone into four horizontal, even slices. Drizzle a little Cointreau or Grand Marnier over the slice (if using).
After softening the butter, gradually beat in the icing sugar until it is completely integrated. To taste, add the lemon juice and zest.
Spread a quarter of the lemon buttercream on the first panettone layer, then continue with the remaining three panettone slices until you have four layers on top of each other with buttercream in between. Finally, use the leftover icing to coat the top and edges of the cake.
After that, create the caramel. Using a vegetable peeler, zest one orange and squeeze the juice from both oranges. In a small saucepan, combine the zest and 90ml of the juice with the caster sugar and cook over medium heat for around 10 minutes. Do not stir; simply shake the pan to verify that all of the sugar has melted. Continue cooking until the mixture turns a deep golden color, being careful not to burn it.
Remove the pan from the heat and rapidly mix in the butter, 1 tablespoon of orange juice, and a pinch of salt.
Remove the zest with a sieve and leave aside to cool for about 15 minutes. It's critical to wait until the caramel has cooled completely to avoid melting the buttercream on the cake.
When the caramel is cold enough to handle, carefully pour it over the top of the cake. Cut into wedges and top with roasted hazelnuts and orange zest.