Bake the Cake:

Preheat the Oven:

• Follow the instructions on the Devil's Food Cake Mix box, baking the cake in a 9x13-inch cake pan.

Poke Holes in the Cake:

• Once the cake is done, while it is still warm, use the handle of a wooden spoon to poke holes all over the top of the cake.
• Set the cake aside to cool slightly.

Prepare the Filling:

Make the Chocolate Filling:

• In a microwave-safe bowl, combine the sweetened condensed milk, heavy cream, and semi-sweet chocolate chips.
• Microwave for 30 seconds to 1 minute, stirring every 20 seconds until the mixture is smooth and the chocolate chips have completely melted.
• The filling should be pourable but not too runny. If it's too thick, reheat it slightly; if it's too thin, allow it to cool to thicken slightly.

Fill the Cake:

• Pour the chocolate mixture into the holes of the cake, spreading the remaining mixture over the top.
• Let the cake cool for about an hour, then refrigerate until completely cooled.
• Make the Marshmallow Whipped Cream Topping:

Whip the Cream:

• In a mixing bowl, whip 1 ½ cups of heavy cream until it begins to thicken.
• Add the powdered sugar and vanilla, then continue whipping until stiff peaks form.

Mix in Marshmallow Fluff:

• Gradually mix in the marshmallow fluff, continuing to whip until fully combined.

Spread the Topping:

• Once the cake has cooled completely, spread the marshmallow whipped cream topping evenly over the cake.

Prepare the Chocolate Ganache Swirls:

Make the Ganache:

• In a microwave-safe bowl, melt ½ cup chocolate chips with 3 tablespoons of heavy cream. Microwave in short intervals, stirring between, until smooth.

Create Swirls:

• Transfer the ganache to a zip-lock bag and cut off the corner.
• Pipe the ganache all over the top of the whipped cream.
• Use a toothpick or skewer to swirl the ganache into a marbled pattern.

Serve:

• Once the ganache is set, serve and enjoy your decadent dessert!