For the French toasts: Place a cast-iron griddle over medium heat. Add the butter and allow to melt until the bubbles subside.
In a large mixing bowl, whisk together the milk, brown sugar, cinnamon, salt and eggs. Gently dip the muffins into the egg mixture; allow any excess egg to drip off. Cook until golden brown, about 1 minute per side. Transfer to a serving platter and shake the confectioners' sugar over the top.
For the whipped cream: In a large mixing bowl, combine the cream, confectioners' sugar, cinnamon and vanilla. Use an electric mixer to whip until soft peaks form.
For the Mexican chocolate sauce: In a mixing bowl, combine the chocolate fudge sauce and cream. Microwave until warm, about 30 seconds. Whisk in the chili powder.
For serving: Serve the French toasts with the whipped cream, Mexican chocolate sauce, maple syrup and dulce de leche.
If not serving right away, keep the French toast warm in the oven at 200 degrees F.