Place 1-quart of water into a 2-quart pot and bring to a simmer.

Place a stainless steel bowl on top of the simmering water, being careful of the rising steam.

Pour half and half into stainless bowl and, stirring frequently, bring the temperature up to about 100 degrees.

In a separate bowl mix egg yolks, sugar and vanilla.

Whisking constantly, slowly add warm half and half to the egg mixture.

Then pour back into the stainless steel bowl (that is over simmering water).

Stir constantly until the custard sauce becomes creamy and coats the back of a spoon (temperature should be about 170°F).

Strain the mixture into a clean container with a lid.

Allow to cool down to 40°F before using.