Begin by creaming the butter with caster sugar until pale and fluffy. Add beaten egg, vanilla extract, salt, and lemon zest, mixing until clumpy. Gradually incorporate flour until a dough forms, then knead lightly. Wrap and refrigerate for 1 hour to firm up.

Roll out the chilled dough on a floured surface until 3mm thick. Cut out circles and place them in tartlet tins, pressing into corners. Chill again for 1 hour, then preheat oven to 180°C (350°F).

Bake pastry shells in the preheated oven for 25-27 minutes or until golden brown. Cool in tins for a few minutes before transferring to a wire rack.

Finely chop chocolate and place in a heatproof bowl. Heat heavy cream until it simmers, pour over chocolate, let sit for 2-3 minutes, then stir until smooth. Let cool slightly.

Fill each cooled tartlet shell with chocolate ganache. Spread evenly and let sit for 10 minutes before refrigerating to set.

Refrigerate filled tartlets for 1 hour. Top with fresh strawberries and optional nuts or sea salt before serving.