Remove stems from apples. Insert a dowel into each apple at the stem end.
In a microwave-safe bowl, combine semisweet chocolate and oil. Microwave at 50% power for 1 minute; stir. Continue microwaving at 50% power in 30-second intervals until melted.
Dollop several spoonfuls of the chocolate on top of an apple around the dowel. Holding dowel, gently tap apple on a flat surface, creating drips. Sprinkle nonpareils over chocolate. Place apple on a parchment-paper-lined baking sheet to dry. Repeat with each apple.