Prepare Cinnamon Sugar: whisk together ½ cup sugar and cinnamon in a shallow dish or pie plate, set aside.
Spoon dough into a pastry bag fitted with a closed rose tip (Wilton 1F or Ateco 846).
Carefully pipe dough into preheated oil, in 6-inch lengths. Use kitchen scissors or tongs to cut off dough from piping bag. Cook 2 or 3 churros at a time. Fry until golden brown, about 4 minutes per side.
Remove churros with tongs to a plate to cooling tray lined with paper towels. Roll churros in cinnamon sugar, and place on a cooling rack.
Repeat process with remaining dough.
Serve warm with dulce de leche or chocolate sauce for dipping if desired.