Line cookie sheet with wax paper.
Break white chocolate into small pieces into medium microwavable bowl. Microwave uncovered on High about 2 minutes, stirring after each minute, or until almost melted. Stir until smooth. Spread on paper-lined cookie sheet to 1/4-inch thickness, about a 13x9-inch rectangle.
Immediately top with snack mix; press into melted chocolate. Let stand about 1 hour, or refrigerate about 30 minutes or until firm. Break into 2-inch pieces. Store tightly covered at room temperature.