1 teaspoon kosher salt, divided, plus more to taste
2 large eggs
6 tablespoons melted unsalted butter
2/3 cup milk
1 tablespoon vanilla extract
2/3 cup granulated sugar
5 tablespoons unsalted butter
3 granny smith apples, peeled, cored, and sliced into thin half moons
Vanilla ice cream, to serve
Preheat the oven to 350°F.*
In a large bowl, combine the flour, brown sugar, baking powder, cinnamon, 1/2 of the salt, eggs, the melted butter, milk, and vanilla extract. Stir until no large lumps remain. Set aside.
In an oven-safe heavy-bottomed pot or cast iron skillet* over low heat, combine the granulated sugar, remaining salt, and 3 tablespoons water. Stir until the sugar has fully dissolved. Bring the mixture to a simmer and allow to cook without stirring until deep amber but not burnt. Add in 5 tablespoons of unsalted butter and stir until smooth.
Reduce heat to low and top the caramel with apple slices. Gently spoon over the cake batter and smooth until even, being careful not to mix in the caramel or apples below.
Transfer to the oven to bake until cooked through, about 30-35 minutes*.
Run a knife around the edges of the cake to loosen the sides from the pot. Cool for at least 10 minutes before inverting onto a serving plate. Serve warm and, if desired, with vanilla ice cream.
You can also cover and bake this recipe on the stove top over low heat if you’d prefer. It generally takes about 30 minutes to cook this way. To test for doneness, insert a toothpick in the cake. If it comes out clean, the cake is done. If not, continue to cook and test every few minutes.