Macarons

Steps

1. 1
   Blitz the ground almonds and icing sugar in a food processor for 15 seconds, then sift, discarding any coarse bits left in the sieve (up to 1 tbsp).
2. 2
   Whisk the egg whites with the salt to soft peaks, then add the caster sugar a spoonful at a time and whisk to a stiff, glossy meringue that holds a straight peak.
3. 3
   Fold the almond mixture into the meringue in two additions, then keep folding, pressing the batter against the side of the bowl, until it falls from the spatula in a thick ribbon that sinks back into itself in about 20 seconds. Stop there: more folding makes the shells spread, less leaves them peaked and cracked.
4. 4
   Pipe 3.5 cm rounds through a 1 cm plain nozzle onto trays lined with baking paper, 3 cm apart. Rap each tray firmly on the worktop three times to release air bubbles.
5. 5
   Leave the shells at room temperature for 30–60 minutes, until a skin forms and they no longer stick to a fingertip. Heat the oven to 150°C (140°C fan).
6. 6
   Bake one tray at a time for 14–16 minutes, until the shells have risen on frilly feet and lift cleanly off the paper. Cool completely on the tray.
7. 7
   For the ganache, heat the cream until steaming, pour it over the chocolate, leave for 2 minutes, then stir until smooth and stir in the butter. Cool until thick enough to pipe.
8. 8
   Pair the shells by size, pipe ganache onto half of them and sandwich with the rest.
9. 9
   Chill in a sealed box for 24 hours before serving: the filling softens the shells to a chewy centre.