In a saucepan over medium-high heat, add the water, butter, vanilla extract, salt, and cardamom. Stir until well combined and butter has melted.

Bring the mixture to a rolling boil, then add the flour all at once and stir vigorously until it forms a dense dough that pulls away from the sides of the pan.

Remove the pan from heat and let it cool for a few minutes. Add the egg and mix thoroughly until you have a smooth, slightly glossy dough.

Transfer the dough to a piping bag (or use a plastic bag with one corner cut off).

In a large frying pan, add enough oil to fill the bottom third of the pan and heat over medium-high heat.

While the oil heats, mix sugar and cinnamon in a shallow bowl.

Once the oil is hot, carefully pipe lines of dough (4-5 inches long) into the oil. Fry for about 4-6 minutes, turning occasionally until golden brown.

Use a slotted spoon to remove churros from the oil, placing them on a paper towel-lined plate.

Immediately roll churros in the cinnamon sugar mixture until thoroughly coated.

Serve warm, optionally with caramel dipping sauce.