Heat 2 cups oil in a large size pot and let the temperature reach at 350 F. Maintain this temperature when cooking your Churro
For the coating, mix together cinnamon and sugar in a shallow plate and set aside.
In a medium sized saucepan, melt butter in a low heat and add in water, sugar, and let boil in low heat. Add the flour and mix until you will for into a smooth batter.
Transfer batter into a mixing bowl, and let it sit for 10 minutes just to cool the batter a bit to not scald the egg. Add the egg and vanilla and mix in medium speed. There will be lumps at first, but eventually the mixture will loosen up and turns smooth. Use a spatula to mix batter to get rid of lumps. You want the batter to be loose so that it will smoothly pipe.
Transfer batter into a piping bag with a 2D tip.
Carefully release/pipe batter into a preheated oil about 3-6 inch long and fry until golden brown
Transfer churro into a paper towel and brown the rest of the batter.
Roll churro into the cinnamon and sugar mixture and this is best serve when HOT.