Truly indulgent, this dessert uses amarene (sour cherries), as well as fresh cherries, and is laced with cherry liqueur for a special kick.
Preheat the oven to 200°C/180°C fan/400°F/Gas 6.
To make the meringue, put 50g of the pistachios in a food processor and blitz until finely chopped. Use a sharp knife to roughly chop the remainder. Set aside.
Sprinkle the caster sugar over the lined baking tray in an even layer. Place the tray in the oven and bake the sugar for about 5–7 minutes, until hot.
Meanwhile, put the egg whites in the bowl of stand mixer fitted with the whisk attachment and add the salt. Whisk on medium speed for about 4 minutes, until the whites are starting to go fluffy.
When the sugar is hot, remove from the oven and lift out the baking paper. With the stand mixer still running on medium, slowly pour the hot sugar into the egg whites. Increase the speed to high, and mix for about 7–8 minutes, until you can no longer feel any grains of sugar between your fingertips. Use a metal spoon to fold in the ground pistachios until evenly combined.
Use a small palette knife to spread the meringue in the prepared Swiss roll tin. Sprinkle over the roughly chopped pistachios. Bake the meringue for 9 minutes to crisp the top. Then turn down the oven to 180°C/160°C fan/350°F/Gas 4 and cook for a further 10 minutes, until firm. Remove from the oven.
Invert the meringue onto the lined wire cooling rack, remove the Swiss roll tin, then slide the inverted meringue back into the tin, and return to the oven for another 6 minutes to finish cooking. Remove from the oven and transfer to a wire rack to cool.
Meanwhile make the cherry filling. Place the amarena and stoned cherries in a small pan with the sugar and kirsch and place over a high heat. Bring to the boil, then reduce the heat to low and simmer for about 8 minutes, until the cherries are tender. Drain through a sieve into a bowl and leave to cool.
To make the cream filling, use an electric hand whisk to whisk together the cream, mascarpone and sugar until thick. Spread three quarters of it over the meringue, sprinkle with a few of the roughly chopped pistachios and spoon over most of the cherry filling. With the short end of the meringue closest to you, use a sharp knife to score a straight line about 2cm in from the short end. Fold along that score line and then roll up the roulade, using the paper to help you.
Place the remaining cream in the medium piping bag with the large star nozzle and pipe rosettes all along the top of the roulade. Decorate with the whole cherries and roughly chopped pistachios.