Use Your Stove
Melt butter in 3-qt. saucepan on low heat. Add marshmallows; stir until marshmallows are completely melted and mixture is well blended. Stir in peanut butter; remove from heat. Add cereal and nuts; mix well. Press firmly onto bottom of greased 13x9-inch pan. Cook remaining ingredients in saucepan on very low heat until completely melted and mixture is well blended, stirring frequently. Pour over cereal; spread to cover. Refrigerate until chocolate mixture is firm.