Crush the graham crackers (I used the bottom of a wide glass cup in a glass bowl and it worked perfectly) and mix in the melted butter and sugar. Pour into the aluminum foil lined pan and push down with a glass cup to make an even layer. Bake for 15 minutes or until the edges are golden brown.
Melt the chocolate in small sauce pan over medium low heat and add half a can of sweetened condensed milk (you can just eyeball it) and the vanilla. Once it is smooth, pour immediately over the graham cracker crust.
Melt the white chocolate chips in a small sauce pan over medium low heat and then add in the marshmallow fluff and the rest of the sweetened condensed milk. Stir until it is smooth and consistent. Immediately pour over the chocolate layer.
Refrigerate overnight. The next day pull the fudge out of the pan using the aluminum foil. Gently remove the foil and carefully cut into squares. Store in the refrigerator if you don't eat it all right off the cutting board.