Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a saucepan, bring butter, water, sugar, and salt to a boil.
Reduce heat and stir in flour until a smooth dough forms and pulls away from the pan.
Remove from heat and let cool for 3–4 minutes.
Add eggs one at a time, mixing well after each addition. Stir in vanilla.
Pipe or scoop small bite-sized dough mounds onto the baking sheet.
Bake for 16–18 minutes until lightly golden and puffed.
Mix cinnamon and sugar in a shallow bowl.
Roll warm churro bites in cinnamon sugar until evenly coated.
Serve warm.