In a medium saucepan, simmer heavy cream and milk. Stir occasionally.
Whisk egg yolks in medium size bowl until they are light in color. Gradually whisk in sugar.
Temper the yolks by slowly whisking in the cream mixture in small amounts until you’ve incorporated about 1/3 of the cream. Pour in the remaining mixture into the yolks and whisk to combine.
Return the entire mixture to the saucepan and cook over low heat.
Continue cooking until the mixture thickens and reaches 170-175 degrees, stirring frequently.
Pour the mixture into a container and let cool at room temperature for about 30 minutes.
Refrigerate mixture for about 4 to 8 hours until the temperature is 40 degrees or below.