Preheat oven to 350 degrees F. Grease a 9x13 baking pan with butter. Set aside.
Combine the dry ingredients: In a large bowl, whisk the flour, baking powder, salt, and ground cinnamon until evenly combined. Set aside.
Combine the wet ingredients and sugars: In another large bowl, mix the eggs, butter (melted and cooled), brown sugar, granulated sugar, Greek yogurt, and vanilla extract.
Combine the dry ingredients with the wet ingredients using a rubber spatula. Do not overmix. Then, fold in the diced apples and the chopped pecans. The batter will be thick.
Pour the batter over the greased pan, and smooth the top over. Bake for 50 minutes or until a cake tester or toothpick inserted inside comes out clean. Cover loosely with foil if it starts to brown too quickly. Mine took 50 minutes.
Meanwhile, make the caramel sauce: Melt all the ingredients, and simmer for 3 to 5 minutes until thickened. Transfer to a bowl to cool slightly.
Remove the cake from oven and let it cool for 30 minutes. To serve, drizzle the top with warm caramel. Enjoy!