In a large bowl add the flour, sugar and salt and stir it together. Chop the cold butter into small cubes and add the cubes in. Use a pastry cutter to further cut the butter into the flour, until it resembles coarse bread crumbs. If at any point the butter begins to melt, place the bowl in the fridge or freezer to cool it down.

In a bowl, lightly whisk the egg. Make a well in the middle of the flour mixture and add in the egg. Use a fork to combine it into a stiff dough. If it is too dry and crumbly add in ½ Tbsp ice cold water as needed. The end dough should hold together but it shouldn’t be wet or sticky.

Tip the dough onto a lightly floured bench and gently form it into a disc. Don’t over knead it. Place the dough into an airtight container and chill it in the fridge for a minimum of ½ an hour until completely cold.

Once chilled, roll the dough out on a lightly floured bench into a 12inch/30cm circle. Dust your rolling pin with flour and roll the pastry around it. Unroll the pastry over a 9inch or 10inch tart tin (23cm or 25cm) and ease it gently into the tin, pressing it into the sides.

Cut off any excess dough at the top and use the excess to patch up any tears in the dough. Use a fork to prick the pastry case bottom. Chill the dough in the fridge again while preheating the oven for blind baking.

Preheat the oven to 338°F /170°C fan bake or 374°F/ 190°C regular oven.

Lay on a sheet of parchment paper on top of the pastry. Add on baking weights to hold it down (see notes or above post for details.) Bake the pastry for around 7-8 minutes. Remove it from the oven and remove the parchment paper and baking weights. Bake the pastry for a further 15-18 minutes until golden brown and baked through.

While the pastry is baking, add the rhubarb, orange juice, zest and sugar to a baking tray. Bake it alongside the pastry for around 15 minutes until softened and sticky.

In a saucepan over medium heat, combine the milk and heavy cream. Heat it slowly until almost simmering.

In a bowl whisk together the sugar, eggs and yolk, orange zest, cornstarch, vanilla paste and salt until it’s well combined.

Slowly drizzle the hot mixture into egg mix, whisking as you do so.
Once all the hot milk has been incorporated, pour everything back into the saucepan and place it over low-medium heat. Keep whisking and bring the mixture back up to a simmer and let it thicken.

Once thick, pour the hot custard through a sieve to remove any lumps, then pour the custard into the baked tart shell.

Use a spoon to scoop up pieces of the baked rhubarb, leaving behind the liquid, and arrange the pieces over the custard.

Place the tart back in the oven and bake for around 15-18 minutes. The custard should still have a wobble to it.

Let the tart cool to room temperature or chill it in the fridge before seving. The custard will set the thickest if it's cooled in the fridge.