Heat the Milk and Cream: In a medium saucepan over medium heat, combine the whole milk and heavy cream. Heat gently until steamy but not boiling.
Mix Egg Yolks and Sugar: In a separate bowl, whisk together the egg yolks, granulated sugar, and salt until pale and slightly thickened.
Temper the Egg Mixture: Slowly pour about half of the hot milk mixture into the egg yolk mixture, whisking constantly to temper the eggs. This step prevents the eggs from scrambling.
Combine and Thicken: Pour the tempered egg mixture back into the saucepan with the remaining milk. Cook over low heat, stirring continuously until it thickens enough to coat the back of a spoon (about 5-7 minutes). Do not let it boil!
Add Vanilla: Once thickened, remove from heat and stir in the vanilla extract.
Cool and Serve: Transfer the custard to a bowl, cover with plastic wrap (pressing it directly onto the surface to prevent a skin from forming), and let it cool. Once cooled, refrigerate until it's set, about 1-2 hours.
