Bring water, butter and salt to a boil then remove from heat and stir in flour until a ball forms.
Add to a stand mixer* and mix on low with a paddle attachment for 1 minute. Then increase speed to medium and add eggs 1 at a time until fully incorporated. *This can also be done by hand.
When cool enough to handle, spoon churro mix into a piping bag with a large star tip.
Heat about 2 inches of oil in a pot to about 360°F and pipe 4 – 6 inch churros into the oil.
Fry, turning once, about 40 seconds per side or until golden then transfer to a towel lined plate and dust with cinnamon sugar mixture. Finish frying the remaining dough.
Meanwhile make your chocolate by heating all ingredients in a sauce pan over medium-low heat. Stir constantly for about 5 – 10 minutes until the chocolate melts and the sauce thickens slightly, careful not to burn. Remove from heat and keep warm.