Start by adding the butter, granulated sugar, kosher salt and water to a small saucepot. Bring the ingredients up to a simmer over medium heat. Turn the heat down to low and add the all-purpose flour. Stir vigorously for about 30 seconds or until the mixture forms a cohesive mass.
Place the dough into the bowl of a stand mixer fitted with a paddle attachment. Mix the dough on low speed for a minute or two to cool it off a bit. Add two eggs, one at a time, and continue to mix on medium speed until the dough reforms into a paste. Alternatively, you can incorporate the eggs into the dough with a large spoon or spatula...this just requires more elbow grease.
Transfer the dough to a piping bag fitted with a star pastry tip. I've found that the Ateco #824 or #825 open star tip works well. A closed star tip with an opening a bit larger would work well too. Avoid using a round pastry tip. Star tips provide a larger surface area on the dough when frying, thus creating a stronger crust (so there's less chance of your churros exploding).
Work out any air bubbles that are visible in the dough, then twist the top of the piping bag to force the dough down toward the tip.
Add the eggs, one at a time, into the dough. Wait for the first one to become totally incorporated before adding the second egg. Continue to mix on medium speed until the dough reforms into a paste–about 30 seconds to a minute. If the pate choux looks broken, give it some extra time mixing and eventually the dough will come together.
Place the pate choux into a pastry bag fitted with a 1/2 inch round tip. Push the dough toward the tip and give the bag a twist, then reserve it.
Pull all of the meat from the chicken bones and discard the carcass. Break down any larger pieces of meat so everything is somewhat consistent in size. Reserve the chicken meat for later on in the recipe.
Heat some neutral-flavored oil to 375-400°F in an appropriately sized pot. The oil you use should have a high smoke point. Peanut, Canola, Corn, Grapeseed or Sunflower oils are all good choices. Only fill the pot 1/3 of the way. Any more and you risk the chance of the hot oil spilling over the sides of the pot when frying the churros.
When the oil reaches temperature, carefully pipe 6 to 7-inch lengths of the churros dough (3 or 4 pieces at a time) into the oil. Do not crowd the pan. Use a pair of kitchen shears dipped in oil to cut the dough.
Fry the dough for 3 minutes per side, then transfer to a baking rack. Repeat the process with the remaining dough.
Toss the churros in the sugar/cinnamon mixture (see sub recipe) while they are still warm. You'll have a hard time get the mixture to stick if the churros cool off too much.
Once all of the dough is fried, serve the churros with some of the dark chocolate sauce (see sub recipe) and enjoy.
Place the heavy cream in a small saucepot and heat it to just below a simmer over medium heat. Add the dark chocolate and turn off the heat. Stir the mixture until it forms a velvety smooth sauce. Place a lid on the pot and reserve it until your ready to serve.
Place both ingredients into a mixing bowl and thoroughly combine.