1. Whisk cream in a mixer bowl until soft peaks form. Add sugar; whisk until stiff peaks form. Transfer to a pastry bag fitted with a 1/4-inch plain round tip (such as Ateco #10); refrigerate up to 30 minutes.

2. Process milk and ice cream in a blender until smooth. Divide among twelve 2-ounce glasses. Pipe spirals of whipped cream on top of milk shakes. Decorate with sprinkles. Serve immediately.