In the stand of a mixer or using a handheld beater, whisk together the ricotta (drained), sugar, vanilla, and cinnamon until smooth. If using chocolate chips, fold them in now. Place the filling in a container and refrigerate until it is time to assemble the sfingi.
To start on the dough, bring the the water, butter, and salt to a boil and then add the flour. Stir until a dough has formed and then remove from heat. Spread the dough out over a cutting board to cool.
Meanwhile, cut out 5-10 approximately 3"x3" squares of parchment paper and prepare a piping bag by fitting your piping bag with the largest star tip you have, or simply cut a ½" whole in the corner of a gallon-sized ziplock bag. Also, begin heating the frying oil in a pot filled approximately 3" deep with oil. You will fry the dough at 275-300 degrees Fahrenheit.
Once the dough has cooled and is no longer hot to the touch (warm is ok), beat in the egg until a smooth dough has formed.
Transfer the dough into your piping bag, and pipe a circular wreath shape onto each parchment paper square. Once the oil has reached a temperature of between 275 and 300 degrees F, gently place the first wreath into the oil while it is still on the parchment paper. The paper will fall off in the oil. Flip the donut over after one minute, or once the underside begins to brown, and cook for one more minute before removing and placing on a plate lined with a sheet of paper towel. Remove the parchment paper from the oil. You can reuse the parchment for more sfingi after it has cooled.
Repeat the piping and frying until you have used up all of your dough. Allow the sfingi to cool before gently cutting open like a bagel and filling with the sweet ricotta cream.
Top with confectioner's sugar and possibly a cherry on top, if desired!