Spray 15x10x1-inch pan with cooking spray. Line pan with waxed paper.
In large microwavable bowl, microwave candy coating on High 1 minute 15 seconds; stir. Continue microwaving and stirring in 15-second intervals until melted and smooth. Stir in pretzels and 2 cups of the candy corn. Spread mixture evenly in pan. Sprinkle remaining 1/2 cup candy corn evenly over top; press in lightly.
Let stand 1 hour or until completely cooled and set. Break into irregular 2- to 3-inch pieces. Store covered at room temperature.