Place the oven rack in the middle of your oven and preheat to 400 degrees Fahrenheit.
Line two baking sheets with parchment paper and spray with cooking spray. Set aside until ready to use.
Combine the water, brown sugar, salt, and butter in a sauce pan and heat over low heat.
Once the mixture starts to simmer, add the flour in all at once and stir vigorously with a wooden spoon to break up the flour and get it fully incorporated. The mixture should come together into a dough ball.
Stir with the wooden spoon vigorously for around one minute, slapping the dough back and forth in the saucepan. Once the film on the bottom of the sauce pan has started to incorporate back into the dough, remove from heat and set aside.
Whisk together the three eggs and the vanilla extract.
Pour a little bit of the egg mixture into the sauce pan and using the wooden spoon, mix into the dough. Adding more of the egg mixture a little bit at a time until it has all been incorporated and the mixture has the consistency of whipped mashed potatoes.
Transfer the mixture to a piping bag with a large star tip.
Pipe the churros onto the prepared baking sheets. The churros can be long or short depending on your preference. Pipe them thick by going slow and applying firm pressure on the piping bag.
Spray the tops of the churros with cooking spray and place in the oven to bake for 20-25 minutes.
While the churros are baking, combine the sugar salt and cinnamon in a gallon size Ziploc bag and set aside.
When the churros are golden brown, turn off the oven and place a wooden spoon in the door to allow the churros to cool slowly. Let cool in the oven for ten minutes
Remove the churros from the oven and place in the Ziploc bag of sugar, cinnamon and salt and shake to coat. Place a few churros at a time to prevent crowding and breaking in the bag.
Serve the churros immediately and consume while still warm.
Churros can be stored at room temperature in an airtight container for a day or so but they're best fresh.