Preheat the oven to 190ºC (170ºC fan oven) mark 5. Lightly spray 8 holes of a muffin tin with a little oil.
Fold each of the filo sheets in half, then cut each into 4 equal-size squares. Use 2 squares to line each muffin hole, then spray with a little oil. Cook for 15 minutes or until lightly golden, then cool in the thin for 5 minutes before transferring to a wire rack to cool completely.
Meanwhile, mix the ricotta and cream cheese together with the yogurt, lemon curd, three-quarter of the lemon zest and all the juice. Chill for 10 minutes.