Warm the milk and cream on low heat just until it starts steaming. You don't want it boiling.
While you are heating the milk, beat the egg yolks and add the sugar. Whisk until completely combined.
Once the milk and cream are warmed, pour a few spoonfuls of the mixture and mix well into the eggs to "temper" them. You want to warm the eggs up without shocking them into turning into scrambled eggs.
Pour the egg mixture into the milk and cream mixture and continue to heat on low stirring often.
It is done when it starts to lightly thicken or when you can run your finger down a the back of a wooden spoon and leave a trace. When it is done mix in the vanilla.
Pour the mixture over your favorite berries and serve!