For the dough: Sift flour, baking powder and salt together.
Place butter and water in a medium pot and bring to boil.
When water has boiled and butter is melted, lower heat and pour in flour mixture all at once, stirring quickly with wooden spoon until a dough is formed. Let dough cool.
For the chocolate sauce: Heat whipping cream and milk in a small pot just until boiling. Remove from heat and pour into a bowl of finely chopped dark chocolate (place in a heat proof bowl).
Stir milk and chocolate until the mixture becomes homogenous. Set aside.
After dough has cooled slightly, transfer to piping bag with a large star tip.
Heat oil up in a pot and when oil is ready, pipe dough into pot. Cut off pieces to your liking.
Fry for 3-5 minutes. When dough is golden brown, remove from oil.
Combine sugar with pinch of cinnamon in a bowl. Coat the churros in the cinnamon sugar.
Serve churros with the dark chocolate sauce on the side.