Cut several parchment papers into squares about 8x8cm and set aside.
In a medium sized saucepan, place the butter, water, sugar and salt and bring to a boil over medium heat. Once it starts to boil remove from the heat. Add the flour all at once, and mix well with a wooden spoon until the flour is combined in the wet mixture.
Return the saucepan back on the stove on medium heat and let it cook while constantly stirring for 2 minutes. Do not move away from this process!
Transfer the cooked dough to a large bowl or to your mixer, let it cool for a couple of minutes. Once slightly cooled, start adding the eggs one at a time, mix and make sure that each egg is fully incorporated in the dough before adding another. If the dough starts to divide after adding the egg, no worries, it's normal, just keep beating.
Fill a large pot with vegetable oil, pour enough oil so that the churros have enough space to cook in, about 7 cm. Heat the oil to about 170°C; you want the oil to be hot enough so that you reduce the cooking time avoiding that they get soggy, but at the same time you don't want the oil too hot that it burns the outside and leaves the inside raw.
Place the dough in a piping bag, fitted with an open star nozzle. Pipe out the hearts on the previously cut parchment papers. Drop the churro with the parchment paper facing up in the oil. Once it's starting to cook remove the parchment paper and let the churro continue to cook for about 2 minutes on each side, until they are nicely golden in colour.
Drain the churros from excess oil on some paper towels, dip them into the cinnamon sugar. Serve them with the thick hot chocolate sauce.