Combine water, butter, sugar, salt, and ground cinnamon in a saucepan over medium heat. Bring to a boil.
Turn heat to low. Add flour and stir until ball forms.
Remove from heat and allow the dough for 5 minutes. Add the eggs and stir until dough forms.
Heat oil to 350˚F.
Put the dough in a large pastry bag with a large star tip. Pipe 3-5 inch strips of dough into the hot oil. Use kitchen shears to cut dough off of the tip.
Fry for 4 minutes, flipping halfway through, until golden brown. Drain on a paper towel-lined plate.
Spray the basket with olive oil and then pipe the dough into strips directly into the basket. Lightly spray or brush the dough strips with olive oil. Set the remaining dough aside for a second batch.
Cook the churros at 380˚F for 10-12 minutes, until crispy.
Remove from the air fryer basket and immediately coat with cinnamon sugar. You can melt butter to brush on the churros before coating them with cinnamon sugar to help them stick better.
Repeat with the remaining batter.
Note 3: Storage
Churros are best when enjoyed immediately after frying them. But if you want to save your leftovers, allow them to cool, and then store them in an airtight container at room temperature for 3-4 days. Reheat in the oven, air fryer, or toaster oven.