Preheat the oven to 180°C. In a large mixing bowl, cream the sugar and butter until pale and fluffy. Add the eggs, one at a time, and mix to incorporate.

Add the vanilla extract and lemon zest, then fold in the flour to make a relatively dense dough.

Grease a madeleine tray and spoon the dough into the moulds, making sure to fill them completely. Bake for 15 to 20 minutes, or until light golden and cooked through. Remove from the oven and leave to cool.

Whisk the icing sugar with a little water, adding more as you go if necessary, to make an icing with a sticky consistency. Drizzle liberally over the madeleines.

To make the strawberry fizz, purée 600 g strawberries with the liqueur and divide between 4 glasses or shallow dessert bowls. Quarter the remaining strawberries and scatter over the purée, then top up with the Prosecco just before serving.