In a very large bowl, combine the 2 packages of milk chocolate chips, the one package of semisweet chocolate chips, both jars of marshmallow cream, 2 teaspoons vanilla extract, Irish Cream, and nuts. Set mixture aside.
Line a 10" x 15" pan with poil and spread lightly with butter or margarine.
In a medium sized saucepan, combine 4 ½ cups of granulated sugar, 1 can of evaporated milk, and ½ pound of butter. Bring to a gentle boil over medium heat and cook slowly, stirring constantly for about 10 minutes.
Pour the milk into the very large bowl holding the chocolate chip mixture. Stir slowly by hand to combine. It is very important to do this by hand and NOT use any kind of mixer.
Pour the fudge into the prepared pan and chill until set.