This chocolate banana upside-down cake combines a glossy brown-sugar caramel, buttery caramelized bananas, and a moist chocolate cake for a decadent dessert you'll want on regular rotation.
Peel the bananas and slice them into ½-inch thick coins on a slight bias.
Melt 2 tablespoons of butter in a wide skillet over medium heat. Once melted and frothy, add the bananas in an even layer, cooking in batches for 2 to 3 minutes per side until browned and caramelized around the edges.
The bananas are ready to flip when they release easily from the bottom of the skillet. Add the remaining 2 tablespoons of butter between batches if needed. Transfer the bananas to a plate and set aside.
Make the caramel:
Preheat the oven to 300ºF. Lightly grease a 9-inch round cake pan. Set aside.
Melt 4 tablespoons of butter in a small saucepan over medium heat. Once melted, add ½ cup of light brown sugar. Stir to combine. Cook over medium heat for 3 minutes, stirring occasionally, until the sugar dissolves and the mixture darkens slightly in color.
Turn the heat to low and add 1 teaspoon of vanilla extract and 2 tablespoons of heavy cream. Whisk until smooth. Simmer for 1 minute. Turn off the heat.
Pour the mixture into the prepared cake pan and smooth it into an even layer. Transfer to the refrigerator for 15 minutes.
Make the batter:
Sift ¾ cup of all-purpose flour, ¼ cup Dutch-process cocoa powder, 1½ teaspoons of baking powder, and ¼ teaspoon of kosher salt into a small bowl. Set aside.
Add 4 tablespoons of room temperature butter and ½ cup of light brown sugar to a large bowl. Use an electric hand mixer to cream them together. Add 2 eggs and beat until smooth.
Add half the sifted dry ingredients and beat with the mixer until just combined. Add half the milk and beat until just combined. Add the remaining dry ingredients and the remaining milk, along with 1 teaspoon of vanilla extract. Beat until just combined. Don’t over-mix!
Gently fold in the peanut butter chips.
Assemble the cake:
Remove the cake pan from the refrigerator. Arrange the bananas over the caramel, overlapping them slightly. Press them gently into the caramel to form a tight layer.
Pour the cake batter on top of the bananas and smooth it into an even layer.
Bake the upside-down cake:
Transfer the cake to the oven and bake for 55 to 60 minutes, rotating it halfway through cooking, until a toothpick inserted into the center of the cake comes out clean.
Let the cake stand at room temperature for 30 to 45 minutes. The cake should still be warm to the touch.
To serve:
Place a large plate over the cake pan and carefully invert the cake onto the plate. Serve with whipped cream and flaky sea salt on top. Enjoy!