Sift the flour, then add the baking powder, salt, and cinnamon and whisk until well combined.
Boil the water, then add it to the dry ingredients and stir for 2-3 minutes, or until the dough is smooth. Use an electric mixer here if you prefer; beat for 1 minute or so on medium speed.
Let the dough rest and cool for about 5 minutes.
Prepare a churrera (churro maker) or a piping bag fitted with a star tip, then fill it with the churro dough.
Pour the oil into a saucepan and set over medium-high heat until it reaches 350°F (177°C).
Once the oil is hot enough, pipe a spiral of churro dough into the oil and cook until browned. Separate the spirals so that they don't stick, and flip the spiral to brown it on the other side.
Once the churro is golden brown, take it out and let it drain on paper towels.
Repeat the process until all the churros have been made.
Cut the spirals into sticks of churros. Serve with hot chocolate or sprinkle with sugar and enjoy them hot and fresh.