Follow the instructions on the package to heat the mini fondue in the microwave.
In a 310 ml (1 1/4 cup)-capacity coffee cup, combine the flour, cocoa powder, brown sugar, baking powder and salt.
Add the milk, vanilla, oil and mini fondue. Stir until well combined.
Microwave for 1:30 to 2:00 minutes, checking for doneness every 30 seconds.
Top with mini marshmallows and the graham cracker.
If desired, use a kitchen torch to brown the marshmallows for a few seconds.
If desired, follow the instructions on the package to heat the mini fondue (from the Toppings section) in the microwave. Drizzle a little fondue over the cake. Store the remaining fondue for future use.