In a large pot, bring 4 cups water to a boil with the lemon zest and cinnamon stick.
In a large mixing bowl, sift together the flour and a pinch of salt. Carefully pour the boiling water into the mixing bowl with the flour mixture. Once all the water has been added, use a wooden spoon to mix the flour and water until it has the consistency of thick oatmeal. Let the mixture cool at room temperature for 10 minutes.
Mix the eggs into the flour 1 at a time, waiting until fully incorporated before adding the next. Add the baking soda, ricotta and sugar and whisk together. Add the liquid mixture to the cooled flour mixture. Using a wooden spoon, stir until the egg mixture is incorporated throughout the flour mixture. This may take a few minutes.
In a 12-inch frying pan, heat 4 cups olive oil over a medium-high flame until hot but not smoking, about 375 degrees F. Working in batches, drop the flour mixture by the tablespoonful into the hot oil. Turn rounds once so that they are golden on each side. As soon as a little fritter is lightly golden, remove from the pan and let drain on a plate lined with paper towels. Work until all the frittelletti mixture has been used, adding more olive oil to the pan if necessary. Serve hot with a dusting of confectioners' sugar.