To prepare the Saint Joseph doughnuts, you need to create the pastry cream first. Heat the milk in a saucepan, adding a half vanilla bean, together with its seeds.
Whisk the egg yolk and sugar in a bowl, then add the flour.
Remove the vanilla bean from the milk using pliers, then pour the warm milk over the egg yolk mix, then start whisking.
Put the mixture back on the stove and stir it constantly, until the cream has thickened.
Transfer the custard to a bowl and let it cool keeping it covered with a foil.
For the dough, place the butter cut into small pieces in a thick-bottomed saucepan, and pour the water. Add salt and bring slowly to a boil, stirring with a wooden spoon.
As soon as the butter has melted and the water starts to boil, remove the saucepan from heat and pour flour inside, using a sifter.
Put the saucepan back on the stove and start mixing with a whisk, then continue stirring with a wooden spoon, to obtain a compact ball.
Keep rolling the mixture until you see a white patina formed on the bottom of the saucepan (it will take around 10 minutes).
Turn off the heat and add the sugar, stir well to incorporate it into the mixture, then pour the mixture into a bowl and let it cool.
Once cooled, transfer the dough in a bowl and add the grated lemon peel and the eggs, one at a time, adding the next egg only when the former is fully absorbed.
Eventually, you will get a smooth and homogeneous composition. Transfer it to a pastry bag with a starry nozzle.
Cut 8 square sheet pans of about 8 cm (3.14 inches) and squeeze over each of them a dough disk, in a spiral, with a 5 cm diameter (1.96 inches).
On the outer edge of each disk. overlay an extra dough "ring", so that you create something resembling a ball with two layers.
Repeat the process for the rest of the 7 doughnuts or so, until the mixture is finished.
In a deep saucepan, place the oil to fry, at a temperature between 160 °C and 170 °C (350-375 F). Don't let the oil boil, as you need to fry the doughnuts gently, turning them upside down several times, so that they are fried evenly.
When the oil has reached the ideal temperature, immerse no more than 1-2 doughnuts, with the parchment paper you placed them on, as it will peel off by itself after a few seconds and you can remove them from the oil with kitchen pliers.
Stir the doughnuts several times in hot oil until golden brown, then drain them with a skimmer. Use towels to remove the excess oil.
When you have fried all the doughnuts, squeeze the custard in a pastry bag with a starry nozzle right at the center of the doughnuts.
Garnish them with cherry syrup, or a candied cherry on top of the cream.
Transfer them on a plate and enjoy the Zeppole di San Giuseppe!