Preheat your oven to 350°F. Grease a bundt pan well with cooking spray to prevent sticking and set it aside.

Pour the melted butter into the bottom of the prepared bundt pan. Sprinkle the dark brown sugar evenly over the butter, then gently stir them together to create a caramel-like base.

Peel the apples, remove the cores, and slice them thinly for even baking.

Arrange the apple slices tightly along the bottom of the pan, overlapping slightly so they form a solid layer.

In a medium bowl, whisk together the flour, baking powder, baking soda, and cinnamon until well blended. Set aside.

In a large mixing bowl, beat the softened butter with the granulated sugar and light brown sugar until creamy and smooth.

Add the vanilla extract and canola oil, mixing until combined.

Beat in the eggs one at a time, making sure each is fully incorporated before adding the next.

Add half of the flour mixture to the wet ingredients and mix on low speed until just combined.

Pour in the buttermilk and mix again.

Add the remaining flour mixture and continue mixing until the batter is smooth, scraping down the sides of the bowl as needed.

Carefully pour the batter over the arranged apples in the bundt pan, spreading it evenly so the apples are completely covered.

Bake uncovered for 25 minutes, then loosely cover the pan with foil and continue baking for another 20 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cake to cool in the pan for 5 minutes. Place a serving plate over the pan and carefully invert to release the cake.

Finish by drizzling caramel sauce evenly over the top before slicing and serving.