For the cream puff shells:
Place oven rack one place below middle. Preheat oven to 400F degrees. Set aside a regular muffin pan (12 or more), very lightly buttered. Note: If you can, use a regular aluminum muffin pan, NOT a dark non-stick pan (see notes for more information). The puffs will be much bigger with the regular silver tin pan.
In a medium sauce pan, bring water and butter to a low boil over medium-high heat. Reduce heat to medium-low and add flour, stirring well until mixture forms a ball. Remove from heat. Stir in eggs, one at a time, beating with spoon or large fork until dough is smooth. Beat additional 10 to 15 seconds as this will increase the volume of the dough.
Using a tablespoon, drop dough into deep muffin tins. This doesn't have to be an exact measurement, but depending on how big you want your shells to be. Divide all the batter between 12 muffins.
Bake shells in 400F degree oven for 25 to 35 minutes or until puffed and golden brown. Important that the puffs are golden/crisp or they may collapse. Even when they look done, I leave them in a full minute or so longer. Remove from oven and cool completely.
(The shells can be prepared the day before. Just lightly cover with foil when completely cooled and let sit at room temperature.)
Cook's note: Ingrid baked the shells on a baking sheet about three inches apart, but my smart aunt decided the muffin tins make a nice shape to hold the cream. Either method works, but Ingrid's way will produce a little flatter shaped shell.
For the custard cream filling:
Place the 4 egg yolks in a medium bowl. Whisk them together and set aside.
Mix sugar, flour and salt in a medium saucepan. Stir in warm milk. Cook over medium heat, stirring frequently. Mixture will thicken and bubble. Once it starts to bubble, cook one minute more while still stirring.
Remove from heat. Quickly whisk about half of the mixture into beaten egg yolks.
Blend this back into remaining hot mixture in the saucepan. Whisk constantly until mixture starts to bubble again. Cook for another 30 seconds or so but do not stop whisking.
Remove from heat and add vanilla (Use good quality vanilla since this flavor is the base of the entire filling.) Set aside, cover with plastic wrap and let cool completely. You can set the custard in the refrigerator to cool quickly. The custard will continue to thicken as it cools.
For the sweetened whipped cream:
Whip your cream using electric beaters or stand mixer and add sugar and vanilla to your liking.
Assembling the cream puffs:
Pour about one cup powdered sugar into a bowl to dip the cream puffs in.
Cut off shell tops and scoop out the insides of top and bottom to make room for the custard and whipped cream. The insides should be moist, almost wet. Totally normal. Just pull that all out.
Dip the bottom of the puff into powdered sugar, then repeat with top of puff. This will coat the puffs more than dusting and gives a "French pastry" decadent look to the finished cream puffs.
Fill bottom of puff with Custard Cream Filling. Top generously with sweetened whipped cream.
Replace top of puff. Place puffs in refrigerator, uncovered, chilling for 4 hours. Do not cover the puffs in fridge or you run the risk of the powdered sugar evaporating. Puffs can remain in the refrigerator overnight this way.
More notes for preparing ahead of time:
You may completely assemble cream puffs the night before serving, they actually get better over time. Cover loosely with foil.
For transporting, place completed cream puffs back into muffin tins, cover lightly with foil and they're ready to go!
Makes 12 cream puffs if made in muffin tin.