Oil and flour three 10-inch Dutch ovens and line with parchment paper. Preheat the Dutch ovens to 350 degrees F (180 degrees C).
Chocolate Cake
Combine the sugar, flour, cocoa, baking powder, and salt in a large bowl.
Add eggs, milk, oil, and vanilla, and beat for 3 minutes.
Stir in the boiling water; the batter will be thin.
Pour the batter evenly into the three prepared Dutch ovens.
Bake for 30 to 35 minutes or until cooked. Cool for 10 minutes, then remove to wire racks to cool completely.
Bananas Foster Filling
Preheat a skillet over medium heat. Melt the butter in the skillet and slowly add brown sugar to make a syrup.
Add the sliced bananas and cinnamon. Stir well, making sure the bananas are completely covered in sauce.
Add the rum to the mixture carefully. Using a lit match, ignite the rum and allow the flame to burn out. Set mixture aside.
Chocolate Frosting
Heat the heavy cream in a small saucepan to a slow boil, about 2 minutes.
Add the chocolate chips and stir well until fully melted, smooth, and well combined with the cream.
Cover and cool for 30 minutes.
To Assemble
Place one cake layer on a serving tray.
Spread half the bananas foster filling on the cake, top with the second cake layer, and spread with the remaining bananas foster filling. Top with the remaining cake layer.
Spread with the chocolate frosting on the top and sides. Place some sliced bananas on top as garnish.