Line 2 baking trays with baking paper. Process the almond meal, pistachios and icing sugar in a food processor until the pistachios are finely chopped, then sift twice. Place the eggwhite in the bowl of an electric mixer and beat on medium speed until frothy, then increase the speed while gradually adding the caster sugar. Beat until stiff peaks form. Mix in enough colouring for desired effect. Fold one-third into the almond mixture and combine well. Gently fold through the remaining eggwhite mixture; it should be glossy and thick, not thin and runny.
Transfer to a piping bag fitted with a 5 mm (¼ inch) plain nozzle and pipe 3 cm (1¼ inch) circles about 3 cm (1¼ inches) apart onto the trays. Leave at room temperature for 1–6 hours (depending on the humidity) or until a crust forms; the macarons should no longer be sticky to the touch.
Preheat the oven to 140°C (275°F/Gas 1). Bake the macarons for 15–18 minutes until they rise slightly. Immediately slide the macarons and paper off the trays onto wire racks to cool completely.
To make the buttercream, place the sugar and eggwhite in the top of a double boiler over medium heat and whisk for 3–4 minutes or until warm and the sugar has dissolved. Remove from the heat. Using electric beaters, beat the mixture on medium–high speed for 6–7 minutes or until glossy and stiff peaks form. Reduce the speed and add the butter, 1 cube at a time, beating well after each addition. Mix in the rosewater and enough colouring for desired effect.
Transfer to a piping bag fitted with a 1 cm (½ inch) plain nozzle and pipe about 1 teaspoon onto half of the macarons. Sandwich with the remaining macarons.
MAKES ABOUT 30
80 g (2¾ oz/¾ cup) almond meal (ground almonds)
40 g (1½ oz) pistachio kernels
220 g (7¾ oz) icing (confectioners’) sugar
110 g (3¾ oz) eggwhite
30 g (1 oz) caster (superfine) sugar
green food colouring, paste or powdered is preferable
ROSE BUTTERCREAM
100 g (3½ oz) caster (superfine) sugar
2 eggwhites
185 g (6½ oz) unsalted butter, cubed and at room temperature
3 teaspoons rosewater
pink food colouring, paste or powdered is preferable