Preheat oven to 425F.
Melt butter in heavy sauce pan over med-low heat with milk, water, salt, and sugar. Bring to simmer.
Once simmering, add all flour at once stirring constantly for about 3 minutes to evaporate some of the water and bring together into a mass that pulls away from the sides of the pan.
Remove from heat. Add eggs one at a time stirring vigorously for 2-3 minutes until smooth and glossy.
Add 2 tsp mounds to a baking sheet lined with a silicon baking mat or parchment paper.
Two options to shape:
Add to pastry bag and pipe with a large star or round tip in a spiral. OR
Use two spoons to form approximate spheres.
Wet fingers can be used to press down peaks or reshape odd lumps.
Bake at 425F for 10 minutes until just starting to turn golden brown. Reduce heat to 375 and bake for a further 8-10 minutes until fully golden brown and crunchy.
Remove from oven then poke a hole in the side of each puff (I suggest a chopstick), allowing remaining steam to escape so that the pastry doesn’t become soggy. Allow to cool completely.