Lakronies
·Toast the hazelnuts
First, we'll make the hazelnut flour. Spread the hazelnuts on a baking tray and toast them briefly (about 5 minutes) in an oven preheated to 200°C. Let them cool for a moment, then rub off the skins.
Grind into flour
Tip the nuts into a food processor, or grind them finely another way. Mix with the icing sugar.
Whip the egg whites with sugar
Whisk the egg whites (best if separated from the yolks at least 24 hours in advance) with the granulated sugar until very stiff. You can add food colouring at this stage.
Don't be alarmed by an unusual colour
One thing to watch out for – for some reason, perhaps because of the hazelnuts, the colour can behave a little differently than usual. For instance, I used violet (Winston's Violet) and the macarons ended up a grey-violet shade.
Fold in the flour
Fold the whipped egg whites together with the sugar and hazelnut flour. Keep folding until the batter no longer drips off the spoon in a thick stream.
Pipe rounds and tap the tray
Line a baking tray with parchment or a baking mat and pipe small rounds, about 3 cm across. Tap the tray firmly on the counter a few times to release any air bubbles, so the macarons don't crack.
Rest, then bake
Let the rounds rest for at least 30 minutes. They're ready for the oven once the surface has dried out and no longer sticks to your finger. Bake at 150°C for about 12–15 minutes.
Filling
Once cooled, peel the shells off the paper and sandwich them with the filling. For the filling: bring the cream to a boil and pour it over the chopped chocolate. Stir until smooth and leave to cool. Then whip in the butter.