Preheat the oven to 450o F.
In a medium saucepan combine the 1 cup water, butter, sugar and salt. Bring the mixture to boil, stirring occasionally with a wooden spoon.
Add the flour to the saucepan, stir. Keep stirring until the mixture pulls away from the side of saucepan. A ball should form around the spoon. Take it off the burner and let it cool slightly.
Add a tablespoon of water at a time and stir to mix after each one.
Scoop a tablespoon of dough, shape it into a ball roughly (be careful the dough will be hot). Place it onto a baking tray, repeat until all the dough is used up. Sprinkle sugar on top.
Bake for 15 minutes. Then reduce the heat to 350o F. Bake further for 25 more minutes. Be careful not to overbake.
Cool the puffs for 15 minutes. Then use a knife to cut the top off of each puff. Fill each puff with a squirt of the icing. Place the top back. Serve and enjoy.