Preheat the oven to 425°F. Bring water or milk, salt and sugar to a boil in a medium saucepan. Add and melt the butter. When the liquid has almost returned to a boil, take the pan off the heat and add the flour all at once.
Turn the heat to low and put the pan back on the stove. Stir the batter until it holds together in one mass, the batter is smooth and you can pull it away from the sides of the pan with a spoon. This should be within a minute or two.
Stop stirring and remove the pan from the heat to cool for 5 or 10 minutes. This is important because you don’t want to cook the eggs that you will put in the batter. Add the eggs one at a time, beating well after each egg until they are fully mixed in and the dough is smooth and no longer slippery.
Use your large hole tip and dot balls onto an ungreased parchment sheet. Bake for about 10 minutes then turn the temperature down to 375°F and continue baking for 15 to 25 minutes, depending on size, until they are golden. Now take each ball and make a tiny slit with a sharp knife near the bottom of the puss and put them back in the oven with the door ajar for about 5 minutes so the steam can escape without softening the shells. Then put them on a wire rack to cool completely before you fill them.