In a 2 quart saucepan combine butter, evaporated milk, sugar and corn syrup. Stir constantly over medium heat until mixture comes to a full rolling boil. Cook for 5 minutes stirring constantly. Remove pan from heat. Stir in chocolate chips, marshmallow and vanilla. Stir vigorously until chocolate chips and marshmallows are melted. Then pour in peanut butter or butterscotch chips and stir just til melted for 30 seconds. Pour into prepared dish. (You can also microwave the peanut butter or butterscotch chips on med-low until melted and then pour onto the chocolate mixture already in the dish in and S-shape, then slide a knife from edge to edge 3-4 times) This allows the fudge to be swirled with peanut butter. Then pour into a buttered 8 x 8 x 2-inch pan. Decorate top with nuts and coconut flakes. Chill in refrigerator until firm. Approx. 1 hour. Cut into squares and serve. Store uneaten fudge in refrigerator.