Heat the water, butter, salt, sugar, and cinnamon over medium heat in a large saucepan until the butter melts completely. Stir then remove from the heat.
Stir in the flour to the butter mixture using a wooden spoon.
Return the mixture to the burner over medium-high heat and cook for a couple more minutes until the dough forms into a ball and a thin layer of flour coats the saucepan. Remove from heat and allow the dough to cool for 5 minutes.
Mix in each egg one at a time so that it's fully incorporated.
Transfer the mixture to a piping bag with a star tip. Once the oil is hot, pipe a steady stream into the oil. Fry for 1-2 minutes. Remove the cooked churros and place them on several layers of paper towels.
Toss in the cinnamon sugar mixture until coated.
Serve plain or with your favorite dessert sauce.