In a large bowl whisk together the flour, baking powder and salt. Make a well in the middle and add the sugar, eggs, zest, vanilla, softened butter, salt and liqueur (or Orange Juice).
Mix together with a fork until almost combined then move to a lightly floured flat surface and knead into a smooth soft dough. Wrap in plastic and let rest 30 minutes at room temperature.
Cut a piece of dough at a time, and roll the dough to form a 1 inch (2 cm) thick rope. Cut the rope in pieces the size of walnuts and roll between your hands to form balls.
Meanwhile, start heating the oil (in a large fryer or deep pot halfway full), make sure the temperature remains between 335 - 345F (170-175C), (too high and they cook on the outside but not in the middle / too low and they remain soggy). Once oil is at the correct temperature, fry a few Castagnole at a time, until they are golden brown and nicely puffed. Approximately 2-3 minutes, but turn often so they brown on all sides. Drain on paper towels, when cool enough to touch, but still quite warm, roll in granulated or turbinado sugar. Serve immediately. Enjoy.
To bake, place the rolled balls on a parchment paper lined cookies sheets and bake for 12-15 minutes in a pre-heated 350F / 180C oven. Once they have cooled dust liberally with powdered/icing sugar.