Preheat the oven to 190C/375C/gas 5. Pulse the flour, salt and butter in a food processor for about 30 secs until it resembles coarse breadcrumbs. Add the egg and turn the mixer on, then drizzle a tiny bit of cold water if needed until the pastry comes together as a ball of dough. Chill in the fridge for 30 mins, then roll out thinly on a floured surface and lay/press into a small tart tin (about 18cm/7in) or 6-8 mini tart tins.

Blind bake the pastry by pricking the base lightly with a fork, lining with greaseproof paper or tin foil and filling with baking beans or rice, then baking in the preheated oven for 5-10 mins. Remove the beans and paper, then return to the oven for a further 5 mins. Allow to cool slightly and fill with the lemon curd.

Using a stand mixer or electric hand mixer, beat the egg whites to stiff peaks, then add the sweetener and whisk again until glossy. Spread on top of the curd and bake in the oven for another 20-25 mins, until the meringue is golden, springy and cooked. Allow to cool completely (or even chill in the fridge to set fully) before serving.