Step 1

For pastry, whiz flour, sugar, xanthan gum and 1/4 tsp salt in a food processor to combine. Add the butter, then pulse again until the mixture resembles fine breadcrumbs. With the motor running, pour in egg and whiz until the mixture forms a soft dough. Shape dough into a disc, enclose in plastic wrap and chill for at least 1 hour or until firm.

Step 2

Knead the pastry briefly so it becomes soft and malleable. Roll out on a lightly floured surface until 3mm thick, then use to line a 20cm fluted tart pan, trimming any excess pastry. Prick pastry base with a fork, then place in the freezer for 15 minutes to firm up.

Step 3

Heat the oven to 180°C. Line the pastry case with pastry weights or uncooked rice. Place pan on a baking tray, then bake for 25 minutes or until the pastry feels dry and firm beneath the paper. Remove the paper and weights, and cook for a further 10 minutes or until pale golden. Glaze the inside of the case with a little beaten egg, then bake for a further 5 minutes or until shiny. Remove from the oven and set aside to cool. Reduce oven to 150°C.

Step 4

Beat the eggs, sugar, cream, lime juice and 150g passionfruit pulp (from about 7 passionfruit) in a bowl. Strain through a sieve into a bowl, pressing down to extract as much juice as possible.

Step 5

Discard solids. Pour the custard into the pastry case, then bake for 40-45 minutes until set, with just a slight wobble in the centre. Set aside to cool slightly, then place in the fridge to chill completely.

Step 6

To serve, combine the remaining passionfruit pulp with icing sugar and drizzle over the tart.