Place the butter, water, salt, sugar (optional) and lemon zest (optional) in a saucepan, whisk gently and bring to a boil over low heat.
When the water is starting to boil add the sifted flour all at once. and vigorously mix the flour in. Using a wooden spoon mix until the dough comes together into a smooth ball that pulls away from the sides of the pan.
Using a wooden spoon mix until the dough and cook for 1-3 minutes, until it comes together into a smooth ball that pulls away from the sides of the pan.
Transfer the dough onto a marble surface and spread it to let it cool. You can also place the dough in a bowl, and then flatten the dough along the sides of the bowl.
Transfer the dough into a bowl. Whisk the eggs in a jar, then slowly incorporate them into the dough, whilst whisking, until you have a creamy, dense shiny dough that is pipeable.
Preheat oven to 400°F/200°C and arrange the oven tray onto the middle shelf.
Transfer the dough to a pastry bag with a large star-shaped tip. Pipe the dough into 3-inch sized circles (you can make one circle or two overlapping ones) onto a tray covered with parchment paper.
Bake the zeppole for 10 minutes, then lower the oven temperature to 360°F/ 180°C and bake for 20 minutes. Open the oven door slightly, and let the zeppole bake for another 5 minutes.
Transfer the zeppole on a cooling rack, then cut them horizontally, and fill them with pastry cream. Close, and pipe more cream on top, decorate with cherries and sprinkle with confectioner's sugar.