In a saucepan over medium heat, combine the water, butter, and salt. Bring to a boil.
Once boiling, remove from heat and quickly stir in the flour until a dough forms.
Allow the dough to cool for a few minutes, then add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
Heat oil in a deep fryer or large pot to 375°F (190°C).
Transfer the churro dough to a piping bag fitted with a star tip.
Pipe 4-6 inch long strips of dough into the hot oil, cutting them off with scissors. Fry until golden brown, about 2-3 minutes per side.
Remove churros from oil and drain on paper towels.
In a small bowl, combine granulated sugar and cinnamon. Roll the fried churros in the sugar mixture while still warm.
Use a piping bag to fill each churro with chocolate hazelnut spread or your desired filling.
Serve warm and enjoy!