Prepare the filling:

1. In a large skillet, heat the olive oil over medium heat. Add the white onion and cook, stirring occasionally, until soft and translucent (about 2 minutes). Add the garlic and cook for about 1 minute.
2. In a large bowl, place the finely shredded chicken and stir in the cooked onion and garlic mixture, salt, pepper, red pepper flakes (optional) , the mayonnaise or Catupiry cheese, and green onions or chives. Set aside. NOTE: If desired, the coxinha filling can be prepared 1 or 2 days ahead and refrigerated in an airtight plastic container.

Prepare the coxinha dough:

1. In a large, non-stick saucepan, place the chicken stock (liquid), salt, annatto or turmeric (optional), and olive oil, and bring to a simmer over medium-low heat. When the stock is hot, add the sifted flour all at once while stirring very well. It will get more and more difficult to stir but continue to stir vigorously for about 1 minute or so until obtaining a uniformly lumpy dough.
2. Remove from heat and transfer the coxinha dough to an electric mixer fitted with a hook attachment. Knead dough at speed “2” for about 5 minutes or until it becomes soft and smooth (NOTE: If you don’t have a mixer with a hook attachment, let dough cool enough to handle and knead by hand very well).
3. Scrape dough from mixing bowl onto a well-floured surface with a dough scraper or spatula, and knead a little bit more by hand. Shape the coxinha dough into a flat disk and let rest for 5 to 8 minutes at room temperature.
4. Using a rolling pin, roll out the dough onto a well-floured surface until it is about ¼ to ?-inch thick. Using a 3-1/4-inch round cookie cutter, cut out disks of dough and place them on a baking sheet lined with parchment paper (a metal spatula can be useful to help pry the disks from the rolling surface). Aggregate the dough leftovers, re-roll, and cut out more disks. With ?-inch thick dough, I was able to cut about 34 disks.
5. Scoop about 1 tablespoon of the chicken filling onto the center of each disk.
6. Lightly oil your hands and shape the filled disks into drumsticks by folding the dough up and around the filling into a beggar’s purse shape, forming the neck of the coxinha between your encircled index finger and thumb, and gently press the filling down into the center as you close. Pinch and seal the edges. Pull the dough at the top out slightly so that it resembles a drumstick.
7. Use a moist towel to clean your fingers off each time they touch the filling. Make sure the dough has no cracks; if it does crack, wet your fingers in water and pinch the dough together. Flatten the rounded bottom of the coxinhas very minimally with the palm of your hand (just enough that they will be able to rest upright), and placed shaped coxinhas on a baking sheet lined with parchment paper.
8. Dredge coxinhas: Prepare three separate bowls for the all-purpose flour, half of the egg whites (i.e. 4 egg whites mixed with 1 teaspoon of water), and half of the breadcrumbs (i.e. about 1-1/2 cups of breadcrumbs). Pass the fritters through each bowl (flour, egg whites, and then breadcrumbs), shaking off any excess. The egg whites and breadcrumbs are divided for use in half-quantities because eventually the bowl of whites will accumulate excess of flour and the crumbs will accumulate excess whites. Both will need to be replaced in order to maintain effective coating of the coxinhas as they are dredged.
9. Fry coxinhas: Pour enough vegetable oil into a frying machine or heavy-bottomed pot. Heat to 350 degrees F. If you don’t have a thermometer to measure the temperature, dip a small piece of the dough into the heated oil. If you hear a sizzling sound, the oil is ready. Fry the fritters in batches. Please, do not place too many coxinhas or chicken fritters in at the same time because this will lower the temperature, making the fritters oily. Make sure to turn all sides while frying the fritters so that they will brown evenly.
10. Transfer coxinhas or fritters to a baking sheet lined with a double sheet of paper towels to absorb any excess oil. To serve coxinhas warm, keep the finished batches in a warm oven until serving.
11. Coxinha can be served by itself or accompanied by ketchup, lime wedges, rosé sauce, or chimichurri sauce. Serve coxinha (s) with a chilled (and authentic) Rioja Dry White Wine, such as 2012 Marqués de Cáceres.