Heat two inches of oil in a deep fryer or a wide saucepan over high heat (about 375˚F).
In a medium saucepan over medium to low heat, add water or milk, butter, and sugar and cook until completely melted.
Lower the heat and gradually add flour, stirring constantly with a wooden spoon until the dough begins to pull away from the edges of the pan.
Allow the mixture to cool off in a large mixing bowl for about 3 to 5 minutes. Add the eggs in one at a time, mixing each one in well with a hand mixer or wooden spoon. (Be sure the dough is warm but not hot as it will cook the eggs.)
When the oil is hot, spoon out the batter with a small spoon. With a spatula, scrape the dough off the spoon and allow it to gently fall into the oil. Do this slowly and carefully to prevent hot oil from splashing.
Fry batches of 6 to 8 doughnuts at a time for about 3 to 4 minutes, or until golden brown. Be sure to turn them at least once so they cook evenly.
With a slotted spoon, remove cooked zeppole from the hot oil and place them on a dish lined with paper towels to cool. Dust with powdered sugar. Serve and enjoy!