1 1/2ozunsalted buttermelted and cooled, plus extra for greasing
3 1/4ozwalnutsroughly chopped
For the Italian Meringue Frosting:
9ozgranulated sugar
5egg whiteslarge
1lbunsalted butter
1quantity salted caramel sauce
For the Salted Caramel Sauce:
5 1/2ozgranulated sugar
pinchsea salt
4fl ozdouble cream
1/4oz salted buttersoftened
Instructions
For the Salted Caramel Sauce:
Melt the sugar over a medium heat until it’s dark brown. Remove from the heat and add the salt and half the cream. It will bubble violently, so take care.
Once it has settled, add the rest of the cream and the butter. If you spot lumps, put the mixture back on the heat and stir. Pour into a heatproof jar to cool.
For the Cake:
Preheat oven to 350 F degrees/180 C. Grease and line three 20 cm-diameter cake tins. In a large bowl, lightly whisk the eggs and sugars together. Put the bowl over a pan of simmering water and whisk until the sugar has dissolved. Take the bowl off the heat and whisk the batter until it forms slowly dissolving ribbons.
Mix the flours, cinnamon and nutmeg in a bowl, then sift a third of it over the eggs and gently fold. Repeat twice more, folding until it’s all just combined. Beat a spoonful of this batter into the melted butter, then fold this back into the remaining batter. Bake in the lined tins for 15-20 minutes. Remove from the oven and, when cool, run a knife around the edge of the cakes and tip onto wire racks.
For the Frosting:
Put 160 ml water and the sugar into a pan over a medium heat. Using a sugar thermometer, bring it up to 250 F degrees/120 C. Whisk the egg whites until they peak and once the syrup is ready, carefully pour it into the whites, whisking constantly until the meringue has cooled. With the mixer on medium-high, add the butter, a few pieces at a time, beating until combined. Mix in about two-thirds of the caramel sauce.
Assemble the cake by putting one sponge layer onto a serving plate. Drizzle it with a little of the caramel, a third of the chopped walnuts and spread over a large dollop of the icing. Repeat with the second layer, then place the final sponge on top. Cover the sides and top of the cake with the rest of the icing. Decorate with the remaining walnuts and the last drizzle of caramel sauce.