1In large microwavable bowl, mix cereals, pretzel pieces and nuts.
2In 1-cup microwavable measuring cup, microwave butter uncovered on High about 40 seconds or until melted. Stir in Worcestershire sauce and seafood seasoning. Pour over cereal mixture; stir until evenly coated.
3Microwave uncovered on High 3 to 4 minutes, thoroughly stirring after every minute. Spread on two 15x10x1-inch pans or paper towels to cool. Store in airtight container.