Preheat the oven to 180°C/gas mark 4 and line a cupcake tray with paper cases.
For the lemon curd, place the sugar and lemon juice in a large bowl, add the eggs and butter and immediately start to whisk. Set the bowl over a pan of just simmering water, being careful the bowl does not touch the water. Continue to whisk until the mixture has thickened then remove from the heat and allow to cool and thicken. Measure out 75g for the cupakes and spoon the rest into a sterilised jar to store.
For the cupcakes, cream the butter, sugar and vanilla seeds together in a large mixing bowl until pale, fluffy and well combined. Crack in the eggs, one at a time, and beat until both are fully incorporated into the mixture. Fold in the flour, fresh lemon zest and candied lemon zest gently.
Place a couple of teaspoons of batter in the bottom of each case, add a teaspoonful of lemon curd then cover with a little more mixture.
Bake the cupcakes in the oven for 15-20 minutes, or until pale golden-brown and spring back when pressed lightly in the centre.
Meanwhile for the meringue topping, make a sugar syrup by dissolving the sugar in the water over a gentle heat. Whisk the egg whites in a clean bowl until soft peaks form and the mixture has doubled in volume. Gradually add the sugar syrup while you continue to whisk, being careful the syrup doesn’t touch the whisk directly. Keep whisking continuously, until the meringue mixture is thick and glossy and has cooled down – check by feeling the side of mixing bowl.
Spoon the meringue into a piping bag and pipe some meringue on the top of each cake. Using a blowtorch, lightly brown the top of each cake to toast the meringue. Decorate with strips of lemon zest and a dusting of icing sugar.