For peppered-walnut meringues, preheat oven to 90C. Whisk eggwhites and a pinch of salt with an electric mixer until soft peaks form. With motor running, gradually add sugar, whisking until smooth and glossy and sugar has completely dissolved (you shouldn’t be able to see any sugar particles in the meringue). Gently fold in remaining ingredients with a large metal spoon and place heaped dessertspoons of mixture onto baking paper-lined oven trays, leaving space between each. Bake for 1 hour, then reduce oven to 70C and cook for another hour. Turn off oven and cool in oven until completely dry. Makes about 12. Meringues will keep in an airtight container for 2-4 days.
Whisk egg yolks and sugar in a large heatproof bowl until pale. Add lemon rind and juice, whisk well to combine, then add butter. Place bowl over a saucepan of simmering water and cook over low heat, stirring continuously with a wooden spoon until thick (8-10 minutes). Cover closely with plastic wrap and cool.
Serve meringues with lemon curd, bittersweet chocolate shavings and whipped cream, if desired.