Heat milk and heavy cream in a saucepan until hot but not boiling.
In a bowl, whisk egg yolks, sugar, cornstarch, vanilla, and salt until smooth.
Slowly pour half of the hot milk into the egg mixture, whisking constantly.
Return all the mixture to the pot and cook over medium-low heat, stirring often, until thickened.
Remove from heat and let cool for 10–15 minutes before serving.
Serve warm or chilled over cakes, pastries, or fresh fruit.