In this recipe, thin, crisp, golden filo pastry shells are filled with unctuous white-chocolate vanilla mousse and topped with tart rhubarb – a heavenly marriage of crunchy, creamy and tangy. Harry and Meghan served rhubarb tartlets at their wedding, which recalled a little taste of Harry’s childhood and the wonderful rhubarb grown at Highgrove.

MAKES 12 tartlets

4 rhubarb stalks

3 tbsp water

50g caster sugar

4 large sheets filo pastry, thawed according to package directions if frozen

flour, for dusting

3 tbsp butter, melted

FOR THE MOUSSE

300g white chocolate, chopped

250g plain Greek yogurt

1 tsp pure vanilla extract

FOR THE DECORATION

12 raspberries

12 small white edible flowers, such as camomile

• Preheat the oven to 180C/ 160C fan/gas 4. Place 12 x 7.5cm fluted round tartlet moulds or a 12-cup standard muffin tin on a baking tray.
• To prepare the rhubarb, trim off both ends of each stalk. If the stalks seem fibrous, peel them. (Rhubarb at the height of the season is usually tender enough not to need peeling.) Cut the stalks on the diagonal into 2.5cm lengths. The pieces will have a lozenge shape. Transfer the rhubarb slices to a baking dish just large enough to hold them in a single layer. Add the water to the dish then sprinkle the sugar over the rhubarb. Cover the dish with aluminium foil. Bake the rhubarb for about 15 minutes until tender when pierced with a fork. Remove from the oven, uncover and leave to cool completely.
• To make the tartlets, lay a filo sheet on a lightly floured work surface, keeping the other sheets covered with clingfilm to prevent them drying out. Lightly brush the entire sheet with some of the butter. Lay a second sheet on top, then lightly brush the top sheet with butter.
• Cut the layered sheets into 6 x 13cm squares. Line 6 of the tartlet moulds with a filo square, pressing the filo down firmly on to the base. Trim the edges where necessary so the pastry does not extend above the rim. Repeat with the remaining 2 filo sheets to line the remaining 6 tartlet moulds.
• Bake the tartlet shells for 10-12 minutes until golden. Leave to cool completely on the tray on a wire rack, then carefully remove them from the moulds.
• To make the mousse, put the chocolate into a heatproof medium bowl over (but not touching) barely simmering water in a saucepan and heat, stirring occasionally, until the chocolate melts and is smooth. (Alternatively, heat in a microwave.) Remove from over the heat and leave to cool. Using a balloon whisk, gradually whisk the yogurt into the chocolate. The mixture may initially curdle, but as you continue adding the yogurt, it will become smooth and thick. Whisk in the vanilla.
• To finish, spoon the mousse into the tartlet shells, dividing it evenly. Drain the rhubarb well and arrange pieces on top of each tartlet, finishing with a raspberry and a flower. Serve within a couple of hours, as the pastry softens if left any longer.