For Beignets: warm the milk in a small pan and add the yeast to it. Stir gently until dissolved.
Put the flour, sugar, and salt in the bowl of a stand mixer fitted with the paddle attachment and blend the dry ingredients briefly.
Set the mixer on low speed and slowly pour in the milk mixture, mixing until the dry ingredients are moistened. Slowly dribble in the eggs, mixing for a few seconds between additions.
Increase the speed and mix until the butter is incorporated and the dough becomes smooth and elastic and pulls away from the sides and bottom of the bowl, about 8 minutes.
Put the finished dough in a buttered bowl, cover with plastic wrap, and refrigerate for at least 3 hours and up to 24 hours.
Dip your hands in the flour and pull off a small piece of dough about the size of a prune. And fry till golden and puffed.it should be slightly springy when pressed at room temperature.
For Sauce: heat milk along with the vanilla extract or bean pod until just about to boil. If you are using bean pod, discard it.
Cream egg yolk and sugar.
Add the warm milk to the egg yolk sugar mix and cook again till it coats the back of the spoon.
Serve 3 pieces with the vanilla sauce drizzled.