Make the churros batter: Place butter, milk, water, (3 gm) sugar and salt in a saucepan over medium heat.
Once the mixture reaches a boil, shoot in the flour and beat with a wooden spoon until combined. Keep beating over a medium-low flame till the dough starts to dry out and is leaving the sides; in particular you will see the dough leave a film on the bottom of the pan.
Transfer the dough to a mixer bowl. Beat slowly to cool the dough until it is almost at room temperature.
In a separate bowl, whisk the eggs to break them up. Add the eggs a little at a time to the cooled dough and beat to combine. (You might not need to add all the egg. Add the eggs only till desired dropping consistency is achieved i.e. it should take 3 seconds for the dough to drop from the spatula and it should hold a soft peak and be smooth and glossy.
Transfer the dough to a piping bag with the desired nozzle.
Mix together 100gm sugar and cinnamon powder. Set aside.
Pipe the churros batter into hot oil and deep fry till golden brown and cooked through. Remove from the oil and toss with the cinnamon sugar.
Serve with chocolate sauce!