Fran's (No Fail) Fantasy Fudge

Combine butter and milk in heavy 2 1/2 quart saucepan. Stir over LOW heat until butter is melted, then add the sugar. Keep on LOW heat, STIRRING CONSTANTLY until mixture comes to a full boil. (Time from sugar melt to full boil is about 15-18 minutes). Continue boiling 4-5 minutes over LOW heat, stirring constantly to prevent scorching. Boil, stirring constantly, until mixture reaches "soft ball" stage (Soft ball stage = a drop of mixture in ice-cold water forms and retains a tear-drop shape; but no more than 5 minutes).
Remove from heat; stir in marshmallow creme until mostly melted, then stir in chocolate pieces until melted. Add vanilla, then stir in the walnuts; beat until well blended and glossy. Pour into greased 13 x 9 inch pan or two 9-inch pie tins. Place the pans on cookie sheet that contains 1/2 inch of ice cold water in order to cool the bottoms quickly. Cool at room temperature; cut into squares. Makes approximately 3 pounds.