1 First make the ganache filling. Heat the cream to just below boiling with the orange zest. Pour the hot cream over the chocolate, leave for 1 minute, stir until smooth, then allow to cool.

2 Cut two sheets of parchment paper to fit two large baking trays. (If you like, draw rows of 4cm circles on the reverse of the paper, as a guide for piping.)

3 Combine the ground almonds and icing sugar in a food processor and pulse to a powder-fine consistency, then pass through a medium-mesh sieve into a bowl. (This is important to remove large pieces of almond skin.)

4 Weigh out the egg whites into two separate bowls. Dip two cocktail sticks in the food colouring and stir colour through the 63g portion of egg whites, then add the coloured whites into the bowl of sieved ingredients. (Lightly mix to a paste with a spatula, avoiding overmixing.)

5 To make the Swiss meringue combine the 50g of uncoloured egg whites and caster sugar in a large heatproof mixing bowl and set it atop a medium saucepan filled with an inch of water. For the next step it is important that the meringue temperature does not rise too far, so if you have a thermometer keep it handy. Heat the saucepan of water and whisk the sugar and egg whites inside the bowl until the sugar has dissolved and the temperature of the mixture turns warm but not actually hot. (Keep it under 50 Celsius). Remove the bowl to a work surface, then use an electric whisk to beat the mixture. Keep to a low speed to start with, then increase to high speed for five minutes, until the merignue is glossy and has a ripple effect. (It is ready once the base of the bowl is cool to the touch.)

6 Fold one-third of the meringue into the almond mixture (two cutting-and-folding turns with a large spatula should be enough), then carefully fold in the remaining third, avoiding overfolding. Stop when the mixture leaves a visible trail when it falls from a spatula (a good indication that the mixture will hold its shape once piped).

7 Fill a piping bag fitted with a 1cm-diameter round nozzle and pipe downwards into circles, leaving a half width between each.

8 Tap the trays on a flat surface to remove air bubbles. Leave the macarons to rest for 20 minutes, to allow a skin to form.

9 Preheat the oven to 190 Celsius on a conventional setting. (Avoid the fan setting). When ready to bake, reduce the oven temperature to 140 Celsius and bake one tray of macarons at a time on the middle shelf for 15 minutes. When baked they will have a "frilly foot" and should not move on the parchment if you press the shell.

10 Once completely cool, gently peel off the parchment. Pipe ganache on to half the shells, then sandwich with a second macaron, flat side down.