Add the heavy cream, milk, sugar, and salt to a saucepan or double boiler and turn it on to medium-low heat.
Whisk constantly while the mixture warms up. When the sugar has dissolved and you see your first signs of bubbles, turn off the heat.
In a separate bowl, whisk your egg yolks. Spoon about ⅓ of the cream mixture into the egg yolks and whisk to combine.
Turn the heat back on the stove and add the egg yolk/cream mixture.
Stir occasionally and let the mixture heat to a low boil. Let it boil for another minute, making sure the temperature reaches at least 170F (77C), but no more than 185F (85C).
Turn off the heat and strain the custard through a fine mesh strainer into a bowl that will go in the refrigerator.
Loosely cover the bowl with it's lid and let it cool down to room temperature. This can take about an hour or so, depending on your home's temperature.
Once it's reached room temperature, let the custard chill in the refrigerator for 4+ hours.