Remove stems from apples. Insert a dowel into each apple at the stem end.
In a microwave-safe bowl, combine semisweet chocolate and 1 tsp of the oil. Microwave at 50% power for 1 minute; stir. Continue microwaving at 50% power in 30-second intervals until melted. Dip apples in chocolate until evenly coated. Allow excess chocolate to drip back into bowl. Place apples on a parchment-paper-lined baking sheet to dry.
In a separate microwave-safe bowl, combine candy melts and remaining 1 tsp oil; melt according to package directions. Dollop several spoonfuls of the candy on top of an apple around the dowel. Holding dowel, gently tap apple on a flat surface, creating drips. Sprinkle M&M's on white chocolate. Return apple to parchment-paper-lined baking sheet to dry. Repeat with each apple.