Set chocolate chips, marshmallow cream, vanilla, Bailey's, and nuts in a very large bowl. Set aside for later. Bring butter, sugar, and milk to a boil and then cook slowly for 11 minutes, stirring constantly. Pour milk mixture over the other ingredients and stir slowly to blend. (Do not use mixer.) Pour into a buttered 9x13-inch or 10x15-inch pan and chill. Makes about 5 pounds.