Preheat the oven to 180°C (350°F). Line a 20 cm (8 in) square baking dish with baking paper. (If your baking dish is smaller, just trim the puff pastry sheets to fit.)

Use a fork to prick the puff pastry sheets all over. Place each sheet on a baking tray, then place another baking tray over the top to stop the pastry rising too high in the oven. (Do this in batches if needed, while preparing the custard.) Bake for 15–20 minutes, until golden, rotating the trays so both sheets brown evenly. Set aside to cool.

Meanwhile, prepare the custard filling. Thoroughly whisk the sugar, custard powder and coconut cream in a saucepan. Set over medium heat and stir until the mixture begins to thicken. Gradually whisk in the coconut milk, until the mixture is bubbling. Switch off the heat and mix in the vanilla bean paste. Leave to cool for 10 minutes before moving on.

Place one cooled baked pastry sheet in the prepared baking dish. Pour the custard mixture over, then top with the second pastry sheet. Sprinkle flaky salt over the top.

In a mixing jug, stir together all the icing ingredients until smooth, then evenly pour the icing over your vanilla slice. Allow to rest in the fridge overnight.

Using a sharp knife, carefully slice into even portions to serve, wiping the knife clean between cuts if you want to keep perfectly photographable layers. The slices will keep for 2–3 days in an airtight container in the fridge before the pastry begins to turn soggy.