Preheat the oven to 155'C.
Pass the almonds and icing sugar through a medium sieve to remove any lumps.
Whisk the egg whites with 150g of caster sugar. Whisk until you have a semi-stiff and glossy meringue.
Stir in one third of the dry ingredients. Once incorporated, repeat with the second third and then the final third. Add the food colouring and work the mixture with a spatula until it is smooth, shiny and a dropping consistency.
Fill a piping bag with the macaroon mix and pipe the macaroons onto a lined baking tray. Tap the tray on your work surface to smooth out the tops and remove any large air bubbles. Leave the macaroons to dry for 15 minutes at room temperature. They are ready to cook when the surface is touch-dry. Transfer to the oven and bake for 10-12 minutes. The macaroons are cooked when the top is firm. Remove from the oven and leave to cool for 10 minutes. After 10 minutes, lift the macaroons from the baking parchment and turn them over. Allow to cool thoroughly before filling.
Mix together the egg yolks, 100g of caster sugar and the cornflour.
Place the milk and the espresso coffee in a saucepan and bring to the boil. Once boiling, add the milk a little at a time to the egg yolk mixture. Return the mixture to the pan and whisk over a medium to high heat for 3-4 minutes, gently bringing it back to the boil. Transfer to a bowl,cover with cling film and chill in the fridge.
Spread the chopped hazelnuts on to a baking sheet, place in the oven and toast until golden brown.
Place the 50g of caster sugar in a frying pan and melt, without stirring, to form a caramel. Remove the pan from the heat and stir in the toasted hazelnuts. Pour the caramel on to a baking sheet and allow to cool and set.
Once cool, crush the caramel into small pieces and fold through the coffee cream.
Fill half of the macaroon shell with coffee cream and top with a second macaroon shell to finish.
«Try making this recipe using chopped almonds or walnuts as an alternative to the hazelnuts.»