Heat the milk, butter, and salt over medium heat until scalded. When the butter has melted, add the flour all at once and beat it with a wooden spoon until the mixture comes together and forms a dough. Cook, stirring constantly, over low heat for 2 minutes. The flour will begin to coat the bottom of the pan. Dump the hot mixture into the bowl of a food processor OR electric mixer. Add the eggs and blend until the eggs are incorporated into the dough and the mixture is thick.
Spoon the mixture into a pastry bag fitted with a plain round tip and pipe in mounds on a parchment lined baking sheet. (Or just scoop even mounds with an ice cream scoop or spoon) You should have approximately 18 puffs. Bake for 20 minutes, or until lightly browned, then turn off the oven and allow them to sit for another 10 minutes, until they sound hollow when tapped on the bottom. Make a small slit in the side of each puff to allow the steam to escape. Set aside to cool.
Whisk together 2/3 cup sugar, ¼ cup cornstarch and a pinch of salt in a medium, heavy bottomed sauce pan. Stir in 3 cups milk and 4 egg yolks. Heat on medium, stirring constantly, until mixture comes to a boil. Boil for 1 full minute. Remove from heat and add 1 tsp vanilla and 1 T butter. Pour into dish and cover with plastic wrap pressed to the top of the cream. Chill.
If a lighter filling is desired, fold in ½ c to 1 cup of whipped cream after the mixture has chilled.
**optional…liqueurs (such as Grand Marnier) can be added with, or in place of, vanilla.
Heat ¾ cup heavy whipping cream to a simmer. Place 1 cup of semi sweet chocolate (I use mini chocolate chips) in a bowl and pour hot cream over the chocolate. Once the chocolate begins to melt, whisk the chocolate and cream until smooth.