Start by making the fudge sauce. Place chocolate bars and cream in a microwave safe bowl. Microwave on high for 30 seconds. Stir until smooth. Set aside.
Meanwhile, whisk eggs and milk in a medium bowl. Melt butter in skillet over medium heat. Dip bread slices in egg mixture and brown each side in skillet.
To make the sandwiches, spread a third of the marshmallow fluff onto one piece of French toast. Place two peanut butter cups on fluff, then place a plain piece of French toast on top. Repeat to make two more sandwiches.
To serve, drizzle with fudge sauce and add candies, plus one chopped peanut butter cup.