Make the custard cream. Mix the granulated sugar amount marked with an ＊ and the egg yolk very well. Add the cake flour and mix it in well too.
Warm up the milk until it's bubbling lightly, and add it to the Step 1 mix. Stir quickly.
Pour the mixture back into the pan through a strainer. Cook over high heat while mixing continously with a spatula. When it starts to bubble, lower the heat to medium, and keep mixing without pausing.
When the custard is cooked through thoroughly, add the butter. Transfer the custard to a shallow tray, cover tightly with plastic wrap, and cool over a bowl of ice water.
Chop up the hazelnuts roughly.
Put 50 g of granulated sugar in a pan, and cook over medium heat until the sugar melts. When it has completely melted and has started to color, add the hazelnuts.
Keep cooking over medium heat while coating the hazelnuts with the sugar. When it all turns a caramel color, take the pan off the heat and spread out onto a baking sheet while it's still hot. Leave to cool.
When the hazelnuts have cooled and the caramel has hardened, put it all into a thick plastic bag, and bash it lightly with a rolling pin.
Cut the sponge cake into 2 1cm thick slices, and cut them out with the glasses you'll be using. Soak them in coffee liqueur (use as much as you like).
Whip the heavy cream until it forms soft peaks, and divide into 3 portions.
Divide the custard cream into 2 portions. Mix 2 tablespoons of the caramelized hazelnuts into one portion with 1/3 of the whipped cream.
Add the instant coffee and 1/3 of the whipped cream to the other half and mix.
Layer the Step 9, 11 and 12 mixture in any order you like in the glasses. End with a layer of whipped cream, which is reminiscent of the foamy milk on lattes.
Top with the remaining caramelized hazelnuts.
Story Behind this Recipe
I wondered if I could make a non-baked sweet using hazelnuts. The caramelized hazelnuts I made were delicious, so I decided to try them in a dessert.
Caramelized hazelnuts are so delicious that you can't stop eating them on their own. If you can keep them tightly sealed so that they don't get humid, they'll keep for a while and are very handy to have.