Start by thoroughly greasing a 10-inch bundt pan with vegetable shortening, then lightly dust with flour. A smaller pan will work, but ensure you never fill more than ⅔ of the pan to avoid overflow during baking.

Melt ½ stick of unsalted butter, either in the microwave or on the stovetop. Pour the melted butter evenly into the prepared bundt pan.

Next, sprinkle the light brown sugar over the melted butter, ensuring it’s distributed evenly.

Using an apple slicer, cut your apple into sections, and then slice each section into thinner pieces, about ¼ inch thick. Remove the peels from each slice. Lay these slices on top of the brown sugar, arranging them side by side around the base of the bundt pan. Depending on the size of your apple or pan, you may need a bit more than one apple to cover the bottom.

Preheat your oven to 325°F (163°C).

Sift the cake mix into a large mixing bowl. Add the instant vanilla pudding mix, eggs, milk, vegetable oil, apple pie spice, and vanilla extract.

Using a hand or stand mixer, blend the ingredients on medium speed for about one minute. Stop to scrape the sides and bottom of the bowl to ensure everything is well incorporated, then mix again for another minute.

Gently fold in the finely diced apples, distributing them evenly throughout the batter.

Carefully spoon or pour the cake batter into the bundt pan, covering the brown sugar and apple layer beneath.

Place the pan into the preheated oven and bake for 45-50 minutes. Keep an eye on the cake as baking times can vary. Test for doneness by inserting a toothpick or skewer into the center of the cake; if it comes out clean or with a few moist crumbs, the cake is ready.

Once baked, allow the cake to cool in the pan for about 10 minutes.

To invert the cake, place your serving plate or cake pedestal on top of the bundt pan, then carefully flip them both upside down as one. Use dish towels or oven mitts to protect your hands from the heat. Let the pan sit upside down for another minute or two to allow the caramelized glaze to soak into the cake.

You may notice a bit of brown sugar sticking to the pan—don’t worry, this is normal.

Enjoy this delicious apple upside-down cake warm or cooled. If you plan to serve it later, store the cake in the refrigerator and allow it to come to room temperature for 2-3 hours before serving for optimal flavor.