Line cookie sheet with waxed paper. In large microwavable bowl, microwave brown sugar, butter and corn syrup uncovered on High 1 to 2 minutes, stirring after 1 minutes, until melted and smooth. Stir in baking soda until dissolved. Stir in cereals.
Microwave on High 3 minutes, stirring each minute. Spread on cookie sheet to cool, about 10 minutes. Break into bite-size pieces.
In microwavable bowl, microwave chocolate chips uncovered on High about 1 minute 30 seconds or until chocolate can be stirred smooth (bowl will be hot). Drizzle chocolate over snack. Refrigerate about 30 minutes or until chocolate is set. Store in airtight container.