Preheat the oven to 350˚F (175˚C). Spray a 9-inch round cake pan (with at least 2-inch tall sides) with baking spray. Line bottom of the pan with parchment paper and spray parchment paper lightly. Set aside.

Pour ½ cup of caramel sauce into the prepared pan. Tilt the pan to cover the bottom of the pan. Sprinkle with the cinnamon then add the diced apple in an even layer. Apples should cover the caramel sauce.

In a large bowl, whisk together the yogurt, sugar, eggs and vanilla until the mixture is smooth. Add the baking powder and salt. Whisk to combine. Add the all-purpose flour. Whisk to combine. It’s okay if there are a few lumps. You’ll work them out after you add the oil.

Pour the batter into prepared pan. Bake for 35-40 minutes, until the cake feels springy to the touch in the center and a toothpick or cake tester inserted into the center comes out clean. Cover loosely with foil if getting too brown near the end and cake is still not done. The best way to test if a cake is done is to use an instant thermometer. The internal temp should be 205-210˚F.

Cool for 10 minutes in the pan then invert the pan onto a plate or platter. Give the pan a firm little shake. You should hear the cake drop onto the plate. Slowly and carefully lift the pan off of the cake. Give a little shout of joy when you see the beautiful cake.