Instructions:

Preheat Oven:
Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan.
Caramelize the Bananas:
In a medium saucepan, melt the butter over medium heat.
Add the brown sugar and stir until dissolved and bubbly.
Pour the caramel mixture into the bottom of the prepared cake pan.
Arrange the banana halves, cut side down, over the caramel in a single layer.
Prepare the Chocolate Cake Batter:
In a large mixing bowl, whisk together the flour, granulated sugar, cocoa powder, baking soda, and salt.
Add the buttermilk, vegetable oil, eggs, and vanilla extract. Beat until well combined.
Gradually add the hot water, mixing until the batter is smooth.
Assemble the Cake:
Pour the chocolate cake batter evenly over the caramelized bananas in the cake pan.
Bake the Cake:
Bake in the preheated oven for 45-50 minutes, or until a toothpick inserted into the center of the cake comes out clean.
Remove from the oven and let the cake cool in the pan for about 10 minutes.
Invert the Cake:
Run a knife around the edges of the cake to loosen it from the pan.
Place a serving plate upside down over the pan, then carefully invert the cake onto the plate.
Let the cake sit for a few minutes before lifting the pan off.

Serve:

Serve the cake warm or at room temperature. Optionally, you can top it with whipped cream or vanilla ice cream.

Enjoy your homemade banana upside-down chocolate cake!