Method
Preheat the oven to 120°C.
Whisk the egg whites to soft peaks, then gradually add the sugar, whisking continuously until thick, smooth and glossy.
Spoon the meringue onto a lined baking tray, shaping into a large round with slightly raised edges. Bake for 25–30 minutes, then reduce the temperature to 90°C and cook for a further 2 hours. Allow to cool completely.
Trim and cut the rhubarb into 3–4cm pieces and place in a roasting dish. Drizzle with honey and water, cover loosely, and roast at 120°C for 25–35 minutes until tender but holding its shape. Cool.
To make the curd, place the citrus zest and juice, butter and sugar in a heatproof bowl over simmering water. Stir until melted and smooth. Add the egg yolks and whole egg and whisk until thickened. Cool, then refrigerate.
To assemble, whip the cream until softly thickened. Spoon over the meringue, followed by the orange curd. Arrange the rhubarb on top, scatter with hazelnuts and candied peel, and finish with primrose flowers if using. Serve immediately.