1. In a mixing bowl, whisk the eggs and sugar together until well combined. 2. In a saucepan, heat the heavy cream and milk over medium heat until it begins to simmer. 3. Slowly pour the hot cream mixture into the egg mixture while continuously whisking to temper the eggs. 4. Return the mixture to the saucepan and cook over low heat, stirring constantly, until it thickens slightly and coats the back of a spoon (approximately 5-7 minutes). 5. Remove the saucepan from heat and stir in the vanilla extract. Let the mixture cool to room temperature.