In a large bowl, combine the popcorn, cereal and nuts. In a microwave-safe bowl, heat butter and honey until butter is melted; stir until smooth. Pour over popcorn mixture and toss to coat.
Transfer to two ungreased 15-in. x 10-in. x 1-in. baking pans. Bake at 350° for 15-20 minutes or until popcorn is golden brown, stirring every 5 minutes. Cool, stirring occasionally. Yield: about 2-1/2 quarts.