Graham Cracker Crust

1. Add the graham crackers and sugar to a food processor and blend into fine crumbs.
2. Blend in the melted butter to create a thick and crumbly mixture.
3. Press the mixture into a 9-inch pie pan. Use a spatula or measuring cup to press it in and around the edges.
4. Place the crust in the refrigerator for at least 30 minutes. While it's chilling, begin the custard filling.

Vanilla Custard Filling

1. Heat the milk and cream together in a medium saucepan until steaming.
2. Meanwhile, whisk the eggs, cornstarch, vanilla, sugar, and salt in a large bowl.
3. Drizzle the hot milk into the bowl of egg mixture slowly while whisking. Once all combined, pour it back into the saucepan.
4. Place it over medium heat. Whisk it continuously as the mixture comes to a boil and thickens.
5. Once the mixture is bubbling and thick, lower the heat to medium-low heat and let it boil for two minutes, whisking the whole time.
6. Take it off the heat and whisk through the cold butter.
7. Carefully pour the custard into the graham cracker base.
8. Place it in the refrigerator to cool further. While it's chilling, begin the berry topping.

Berry Topping

1. In a medium saucepan, combine 2 tablespoons of cold water with the cornstarch. Mix it into a slurry.
2. Add the berries, sugar, lemon juice, zest, vanilla, and salt.
3. Place the saucepan over medium-low heat and stir regularly as the mixture begins to warm up.
4. As the mixture boils, it will thicken, become jelly-like, and lose its cloudy appearance. Let it boil for around 2 minutes, stirring continuously, before taking it off the heat. The cornstarch must be cooked through properly, or the filling can lose its thickness.
5. Let it cool for 10 minutes, then scoop it onto the custard. Place the pie back in the refrigerator and chill for at least 5 hours or overnight.