1. Build an ice bath and set aside. Put the egg yolks in a medium mixing bowl and set aside.
2. In a medium saucepan over medium-high heat, combine the milk, sugar and salt. Bring to a simmer and cook, stirring until the sugar has dissolved, about 5 minutes. Remove from heat and, a little bit at a time, gradually ladle the hot milk into the egg yolks, whisking to prevent the yolks from curdling. Pour the mixture back into the saucepan over medium heat and stir continuously until the mixture coats the back of a wooden spoon, about 4 minutes. Remove from the heat and, if there are any lumps, strain through a sieve.
3. Combine the hot custard and cream together and transfer to a 1-gallon resealable freezer bag; seal and submerge in the ice bath until completely chilled, about 20 minutes.
4. Pour the chilled base into the pre-chilled bowl of the ice cream machine and follow the manufacturer's instructions to churn until the mixture is a soft-serve ice cream consistency, about 30 minutes.
5. Using a rubber spatula, transfer the ice cream to an airtight container and press a sheet of parchment directly onto the surface of the ice cream. Cover the container with a lid and freeze until the ice cream is firm, 3 to 4 hours.
Vanilla Ice Cream: Add one vanilla bean, split lengthwise, seeds scraped, to the hot milk-egg mixture in step 2 and allow to infuse for at least an hour before discarding the vanilla bean. Add a teaspoon of vanilla bean paste or vanilla extract. And continue with steps 3, 4 and 5.
Strawberry Ice Cream: Combine 1 pint of strawberries (hulled and quartered), 2 tablespoons sugar and 2 tablespoons of liquid (such as lemon juice, rosé or orange blossom water) in a small saucepan and cook until the strawberries have broken down and released their juices, about 15 minutes. Chill the strawberry syrup, then add to chilled ice cream base before churning in an ice cream maker in step 4. Continue with steps 4 and 5.
Chocolate Ice Cream: Combine ⅓ cup of unsweetened cocoa powder and ⅓ cup roughly chopped semi-sweet or bittersweet chocolate to the hot milk-egg mixture in step 2. Remove the saucepan from heat and stir until the chocolate has completely melted. Continue with steps 3, 4 and 5.