Line a 9-inch square baking dish with parchment paper or aluminum foil. Make sure to leave an overhang so that you can easily remove the fudge from the pan.
In a saucepan, bring sugar, butter and evaporated milk to full boil, stirring constantly.
Cook for 1 minute, stirring constantly.
Remove from heat.
Stir in chocolates and marshmallow crème until melted and well-combined.
Add vanilla and mini marshmallows. Stir until melted and combined.
Line the bottom of the pan with pieces of graham cracker.
Pour half of the fudge over the graham cracker pieces.
Place another layer of graham crackers over fudge.
Pour the remaining half of the fudge in, and top with remaining graham cracker pieces.
Let cool before cutting.
I also chilled mine for about 30 minutes to make it easier to cut.