In a heavy-bottomed saucepan, add the milk and on a medium-low heat, bring it to a simmer. In a small bowl mix your cornstarch and water, stir well and keep ready.
Meanwhile, in a separate heat-safe bowl
add the eggs, sugar, salt, and vanilla and whisk well. When the milk reaches a simmer, pour the milk little by little, slowly, whisking continuously. Keep going till all the milk is poured.
Return the milk to the saucepan on the heat and keep whisking, add the cornstarch slurry and continue whisking until the mixture thickens. Remove from the heat. Transfer it to a heatproof bowl, cover with cling wrap making sure the cling film touches the custard. Let it cool down to room temperature and then refrigerate it.
Make the crust:
Add all the ingredients for the crust into a food processor and mix until well combined and when you press the mixture between your fingers they retain the shape.
Press this into a 9inch removable bottom tart shell. Bake in a preheated oven for around 10 minutes at 170 C.
Remove and leave to cool completely.
Assemble the tart:
Once the crust is cool completely and the custard is set, add the orange zest to the custard and whisk it to combine. Pour the custard into the tart shell and even it out with an offset spatula or a spoon.
Chill in the refrigerator or freezer for 30 minutes, top with your favourite fruit. Refrigerate for a minimum of 3-4 hours or until set. Serve and enjoy fresh!