In large microwavable bowl, place cereals, pretzels and peanuts; set aside.
In 2-cup microwavable measuring cup, microwave brown sugar, butter and corn syrup uncovered on High about 2 minutes, stirring after 1 minute, until melted and smooth. Stir in baking soda until dissolved. Pour over cereal mixture, stirring until evenly coated.
Microwave uncovered on High 1 to 2 minutes, stirring and scraping bowl every 30 seconds, just until cereal begins to brown. Cool 5 minutes; stir in candies. Spread on waxed paper to cool; break into bite-size pieces. Place in gold foil baking cups if desired. Store in airtight container.