1 c. water
2 T. milk
1/2 c. unsalted butter
1 T. sugar
pinch of salt
1 c. flour
Preheat oven to 425 degrees. Line two sheet pans with parchment paper.
Bring the water, milk, butter, sugar, and salt to a boil in a sauce pan. Remove from heat and add the flour all at once. Stir with a wooden spoon until all the ingredients come together. Place back on heat and continue to stir briskly and cook until the mixture comes together and pulls away from the sides of the pan.
Add three of the four eggs and continue to beat until the ingredients come together. Add the last egg and mix until smooth and glossy.
Fit a pastry bag with a plain, wide tip.
Fill the pastry bag with the pate a choux paste and pipe small mounds onto a parchment-lined sheet pan.
Brush the tops with an egg wash, using the brush to smooth out the tops and pat down any pointy peaks - they like to burn.
Bake for 8 minutes at 425 then decrease oven temperature to 350 degrees and cook for another 20 minutes, checking after 10 minutes. If they are getting too brown too fast, reduce the oven temperature even more to 310 degrees.
The puffs need the initial high heat to give them their height. After that you are cooking the insides and drying them out - forming the open space inside for your fillings.
Remove from oven and let cool. You can either fill by inserting the tip of a pastry bag directly into the shell and squeezing the filling inside or you can cut them in half and fill them that way.