1. To make the pastry, mix the icing sugar and flour in a bowl.
2. Using your hands, rub the butter into the flour mix until crumbly.
3. Mix in the egg yolks.
4. Roll into a ball, flatten out in your hands, wrap in cling film, and leave for at least 30 minutes while you get started on your filling!
5. For the filling, beat all the ingredients (excluding the zest) together.
6. Sieve the mixture and then add the zest.
7. On a lightly floured surface, roll out the pastry to the thickness of a £1 coin, then lift into a tart tin.
8. Press down on the bottom and sides and trim off any excess pastry.
9. Poke a few holes at the bottom with a fork and put back into the fridge for another 30 minutes.
10. Heat the oven to 160C.
11. Line the tart with foil and fill with rice or dried beans and bake for 10 minutes.
12. Remove the tart tin from the oven, discard the foil and bake for another 20 minutes until biscuit.
13. When the pastry is ready, remove from the oven, pour in your lemon mixture and bake again for 30-35 minutes until just set.
14. Leave to cool, then remove from the tin, top with Joe & Seph’s Orange Marmalade Popcorn and dig in!