In a medium saucepan, combine water, butter, brown sugar, and salt over medium heat. Stir until mixture simmers and the butter melts, about 3-5 minutes. Gradually mix in flour, stirring vigorously until a cohesive dough forms.

Remove saucepan from heat and let dough cool for about 10 minutes. Add eggs one at a time, mixing vigorously until dough becomes smooth and glossy.

Preheat oven to 425°F (220°C). Line baking sheets with parchment paper. Pipe 3-4 inch long ropes of dough onto prepared sheets, leaving 2 inches between each churro.

Lightly spray churro shapes with oil. Bake for 20-25 minutes until golden brown and firm. Do not open the oven door during baking.

Turn off oven and let churro bites sit with door ajar for 10 minutes. Combine granulated sugar and cinnamon. Brush churro bites with melted butter, then toss in cinnamon-sugar mixture until coated.