In a saucepan, combine margarine, sugar, salt, and water. Bring to a boil, allowing the margarine to melt. Add in flour all at once; mix with a non-metal spoon to form a ball of dough. Remove from heat; transfer dough to the bowl of an electric mixer.
With the mixer running on low speed, add eggs, one at a time, until eggs are fully incorporated.
Heat oil in a deep fryer to 350ºF. Add batter to a piping bag fitted with a 6B tip or any similar wider tip with ridges. Now, at this point you can prepare the batter ahead and leave the piping bags in the fridge until you’re ready to fry.
Pipe into hot oil: Using a knife, cut batter at about every 4 inches, allowing strip to drop into oil. Repeat, frying in batches of 6 churros until golden, about 4 minutes. Drain on paper towels. You’ll get curved or S-shaped churros*
Meanwhile, mix cinnamon and sugar in a shallow dish. Roll churros in mixture while they are still hot.
Notes
*Make ahead and if you’d like perfectly straight churros: pipe them onto a parchment-lined baking sheet. Freeze for at least 30 minutes, or until the day of the party when you’re ready to fry. If freezing until the day of the party, you can transfer frozen piped churros to a bag for easier storage. When ready, fry them straight from the freezer.You can make the batter earlier in the day and keep refrigerated in the piping bag, then fry fresh. If serving Friday night, fry earlier in the day and rewarm uncovered.If you do need to make them completely ahead of time, store them in a covered container at room temperature or freeze. Don’t refrigerate. Then, warm them uncovered in the oven (in a single layer on a baking sheet is best) for about 5 minutes (or longer if frozen). This way, they stay crispy.Yield around 50 long churros or 75 shorter ones.