LA Notes - I did not have a vanilla bean so I just used a teaspoon of vanilla extract.
It is VERY important that you do not let it boil as you are cooking it - it will curdle and you will have to start over - guess how I know that?!
Combine the milk and vanilla bean in a small saucepan.
Heat over medium-high heat until small bubbles form around the edge.
Remove from the heat, cover, and infuse the milk for 10 minutes.
Scrape the seeds of the bean into the milk.
Rinse and dry the bean and save for another use (such as putting it in your bag of sugar, which will turn it into vanilla sugar).
Whisk the egg yolks with the sugar and salt in a large heatproof bowl until thick and light, 3 to 4 minutes.
Stir in the hot milk.
Return the custard to the pan and stir over low heat until slightly thickened or until a finger drawn across a wooden spoon dipped in the sauce leaves a mark (about 160 degrees F).
Do not boil, or the sauce will curdle.
Strain into a large bowl and cool to room temperature.
Cover with plastic wrap and refrigerate until well chilled, at least 2 hours.
Serve over top of Snow Pudding.