Place the flour, icing sugar, salt, lemon zest and butter into a food processor. Blitz until the mixture resembles fine bread crumbs.
Add in the egg and egg yolk and mix until the dough comes together.
Turn the dough onto a lightly floured surface and kneed the dough briefly to bring it all together.
Form the dough into a ball, wrap in glad wrap and place it into the fridge for about 45 minutes.
Remove the dough from the fridge and roll it out between 2 sheets of baking paper, to a thickness of about 2mm. Transfer the dough to a baking tray and refrigerate for another 20 minutes.
Remove the pastry from the fridge again and use a 6cm round cooker cutter to cut out 24 discs from the dough. Line 2 x 12 mini muffin tin trays with the pastry discs. Place the tarts back into the fridge for another 20 minutes.
Blind bake the tarts at 170 °C for 20 minutes. Remove the beans from the tarts and bake for an additional 2 minutes to try out the casings.
Remove from the oven and leave to cool. Remove the tart casings from the muffin trays and brush generously with melted chocolate on the inside. Place to the side until needed.