Whisk the flour, baking powder and salt together in a medium bowl.
In a large bowl whisk together the granulated sugar, brown sugar and eggs.
Whisk in the cooled, melted butter until combined followed by the sour cream and vanilla.
Add the dry ingredients to the wet ingredients and stir until just combined.
Pour the batter over the apples in the pan and carefully spread over the top.
Bake in the preheated oven until the cake is golden brown and a toothpick comes out clean – about 40 – 45 minutes. Rotate the pan halfway through baking.
Let the pan cool on a wire rack for 20 minutes.
Run a knife around the edge of the cake pan and invert onto a rack. Be sure to have a piece of wax paper or foil underneath to catch any runoff. Have some patience as it will take about a minute for the cake to release.
Scrape any apples and caramel that remained in the pan onto the cake.
Let the cake cool for about 20 minutes before serving.
Serve with whipped cream or vanilla ice cream if desired.