1. In large microwave-safe bowl, melt butter at high, 15 to 30 seconds. Stir in cinnamon and syrup.
2. Add KELLOGG’S® CRISPIX® cereal. Toss to coat evenly. Microwave at high 1-1/2 minutes, stirring every 30 seconds. Spread on waxed paper; let cool 5 minutes. Return to bowl.
3. Add marshmallows and chocolate morsels. Toss to mix. Store in airtight container.