Creating the Banana Upside Down Cake is simple and straightforward. Follow these steps for a delicious outcome:

1. Preheat Oven: Begin by preheating your oven to 350°F (175°C). Grease a 9×13-inch baking pan or a round cake pan.
2. Prepare Topping: In a saucepan, melt the butter over low heat. Once melted, add the brown sugar and stir until dissolved. Pour this mixture evenly into the bottom of the prepared pan.
3. Layer Bananas: Place the sliced bananas on top of the sugar mixture, arranging them in a single layer.
4. Mix Dry Ingredients: In a large bowl, whisk together the flour, granulated sugar, baking powder, baking soda, and salt until well combined.
5. Mix Wet Ingredients: In another bowl, combine the sour cream, vegetable oil, eggs, and vanilla extract. Whisk until smooth.
6. Combine Mixtures: Gradually add the wet ingredients to the dry ingredients, mixing until no lumps remain.
7. Pour Batter: Carefully pour the batter over the arranged bananas, spreading it evenly.
8. Bake: Place the pan in the preheated oven and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
9. Cool: Once baked, remove the cake from the oven and let it cool for 10-15 minutes in the pan.
10. Invert Cake: Carefully invert the cake onto a serving platter, allowing the bananas to be on top.

This process will ensure an incredibly moist and flavorful banana cake that will impress everyone!