Transfer dough into a piping bag with a 1/3-inch star tip nozzle.
Grease 6 cream horn molds with oil and place onto a baking tray. Starting at the bottom of the mold, pipe batter around the horn molds and then freeze for 4 hours.
Heat oil over medium-high heat in a wok or small, deep saucepan.
Cook the cones, still wrapped around their molds, for 2 to 3 minutes or until golden, turning occasionally.
Remove onto a paper towel-lined plate to drain. When cool enough to touch, remove the molds (you may need to use a knife to loosen). Roll in cinnamon sugar, and leave to cool completely before topping with a scoop of chocolate ice cream.