Line an 8-inch square baking dish with foil, and lightly spray with cooking spray.
In a medium saucepan over low heat, stir together the evaporated milk, homemade marshmallow cream, butter, both sugars, and salt. Gently stir until the sugars are dissolved. Once dissolved, turn up the heat to medium, stirring constantly, allow the mixture to come to a boil. Clip a candy thermometer to the side of the pot, continue to gently stir until the mixture reaches about 230 degreed F (110 degrees C), about 6 to 10 minutes. The sugars will caramelize, and thats okay, just keep stirring constantly.
Remove from heat and add in both chopped chocolates and gently stir until completely melted. Stir in the vanilla. Keep stirring the fudge until it goes from shiny to matte. Spread the fudge into the prepared pan and let it cool to room temperature. Before it sets completely, about 20 minutes later, sprinkle on the fleur de del evenly on the fudge.
Once completely cool, divide the fudge into equal piece in the size of your preference. It is rich, so a little goes a long way.
The fudge can be stored at room temperature, tightly covered, for up to 1 week.