Combine Butter, Sugar And Milk In A Large Pan And Stir Until Dissolved. Stir A Few Times Until It Comes To A Boil. Cover And Let Boil For Five Minutes Without Stirring. Remove From Heat. Add Marshmallows And Stir Until Dissolved. Add Chocolates, One At A Time Until Melted. Add Vanilla Extract And Nuts. Pour Into A Lightly Greased Ten By Fifteen Inch Pan. Refrigerate And Cut Into Small Squares.