Preheat the oven to 180C (160C in a fan oven) Gas 4.
Lightly grease a 12-hole muffin or cupcake tin.
Take 2 sheets of filo pastry, one at a time, brushing each sheet with butter before laying the next one on top. Cut the filo pastry in half lengthways and cut each half into 3 squares.
The squares should be big enough to fit into the muffin holes and hang over the sides a little.
Repeat the process to fill all 12 holes. (the remaining pastry can be kept in the freezer for another day, or make another 6 tartlet cases – they can be kept in an airtight container for up to 3 days).
Place the filo cases into the oven for 4-6 minutes until they are lightly golden and crisp.
Remove them from the oven, transfer to a cooling rack to cool completely.
In a large bowl, mix the lemon curd, mascarpone and yoghurt.
Fill the filo cases with the lemon mixture and top with fresh raspberries.
Decorate with a dusting of icing sugar and fresh mint.