Make the cream filling:

1. In a medium saucepan, pour in the milk and heat over medium heat until simmering.
2. Meanwhile, while milk is heating up, add the egg yolks and sugar to a large mixing bowl and whisk rapidly for about 1 minute, or until the mixture looks paler. Sift in the cornstarch, then whisk again until smooth.
3. Once the milk is simmering, slowly drizzle the hot milk into the egg mixture, while whisking simultaneously.
4. After all of the milk has been added, pour the custard back into the pot through a fine mesh sieve to remove any lumps.
5. Place the custard back over medium heat, then heat until bubbling. Once bubbling, continue to cook for exactly 1 minute, then remove from the heat.
6. Add in the butter and vanilla, then whisk to combine.
7. Transfer to a heat-proof bowl, cover the surface with plastic wrap, then place into the fridge for at least 4 hours or overnight.

Make the sugar cookie crust:

1. In a large mixing bowl, add the butter, sugar, and salt. Beat with an electric hand mixer until fluffy and pale, about 2-3 minutes. Add in the egg yolk and vanilla, then beat again until well-combined.
2. Add in the flour and beat until combined, and a soft dough comes together (it may seem dry at first, but keep mixing and a dough will eventually form).
3. Use your hands to gather the dough together and shape it into a disc. Wrap the dough tightly in plastic wrap and place into the fridge to rest for 30 minutes.
4. Preheat the oven to 350F.
5. After the 30 minute rest, remove the dough from the fridge and unwrap it. Place the dough onto a lightly floured work surface and use a rolling pin to roll it out into  a 10.5-inch circle.
6. Carefully transfer the dough into a 9-inch tart pan. Press the dough into the bottom of the pan and along the sides. Use a paring knife to cut off the excess dough.
7. Place into the oven to bake for 28 minutes. Allow the crust to fully cool before adding the filling.

Assemble the tart:

1. When ready to assemble, place the crust onto a serving platter. Spoon the custard into the cooled crust. You can also transfer the crust into a piping bag with a large round tip and pipe the custard into the crust.
2. Arrange the fruit on top of the custard.
3. In a small mixing bowl, combine apricot jam and water. Stir until fully mixed. Use a pastry brush the fruit with the watered-down apricot jam. Keep cool until ready to serve.