Upside-Down Banana Cake

Preheat the oven to 350 F. Grease a 9-inch spring form pan. Set aside.
Make the caramel topping. Place the granulated sugar in a large, deep saucepan over medium heat. The sugar will begin to melt. Give it a couple of stirs to evenly distribute the heat. When the sugar turns golden brown, add the butter and salt. Be careful when you do this-the sugar will bubble and spit. Stir until the caramel is smooth. Remove from heat.
Spread the caramel on the bottom of the pan. Work quickly, since the caramel will set quickly.
Slice the banana into 1/2-inch thick pieces. Place on the bottom of the cake pan, laying the slices flat on the bottom.
Now make the cake batter. In a medium-sized bowl whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large bowl cream together the butter and sugar until it is light and fluffy. Beat in the eggs and vanilla.
Fold about 1/3 of the dry ingredients into the butter/egg mixture. Mix in 1/3 of the buttermilk.
Alternate between adding the two until both are entirely incorporated. Pour the batter into the cake pan and gently smooth the top.
Bake the cake for 1 hour to 1 hour 15 minutes, or until a toothpick inserted in the middle of the cake comes out clean. Remove pan from oven and let it sit in the pan for a few minutes then invert it onto a large serving tray.
Cake batter recipe adapted from Smitten Kitchen.