Follow these steps to create your Easy Caramel Apple Upside-Down Cake:

1. Preheat the Oven: Begin by preheating your oven to 350°F (175°C). Grease a 9-inch round cake pan with butter or non-stick spray.

2. Prepare the Caramel Mixture: In a saucepan, melt the butter over medium heat. Stir in the brown sugar and cinnamon until well combined. Cook for about 2-3 minutes until the mixture is smooth and bubbling.

3. Arrange the Apples: Pour the caramel mixture into the prepared cake pan. Arrange the apple slices evenly over the caramel, overlapping them slightly if necessary.

4. Mix Dry Ingredients: In a large mixing bowl, whisk together the flour, granulated sugar, baking powder, baking soda, and salt until well mixed.

5. Combine Wet Ingredients: In another bowl, combine the buttermilk, eggs, and vanilla extract. Whisk until fully combined.

6. Combine Mixtures: Gradually add the wet ingredients to the dry ingredients, stirring until just combined. Be careful not to overmix; a few lumps are okay.

7. Pour Batter: Carefully pour the batter over the arranged apples in the cake pan, spreading it evenly.

8. Bake: Place the cake in the preheated oven and bake for 40-45 minutes, or until a toothpick inserted in the center comes out clean.

9. Cool the Cake: Remove the cake from the oven and allow it to cool in the pan for 15-20 minutes. This will make it easier to invert later.

10. Invert the Cake: Carefully run a knife around the edges of the pan. Place a serving plate on top of the cake pan and quickly flip it over to release the cake. Gently tap the pan to ensure the cake comes out.