Beat the egg yolks and the sugar in the bowl of a stand electric mixer fitted with a paddle attachment on medium high speed for 3 minutes, or until very thick.

Reduce to low speed, and add the cornstarch.

With the mixer still on low, slowly pour the hot milk into the egg mixture.

Pour the custard mixture into a saucepan and cook over low heat, stirring constantly with a wooden spoon, until thickened.

The sauce will coat the spoon like heavy cream.

Don't cook it above 180°F or the eggs will scramble.

Pour the sauce through a fine mesh strainer.

Add the vanilla extract, Cognac, and vanilla seeds, if using, and chill.

*To scald milk, heat to just below the boiling point.*

**This dessert sauce tastes delicious over cakes and other desserts of your choosing.*