Position the oven rack to the middle position of your oven. Preheat the oven to 350 °F (175 °C) and place a piece of parchment paper over a 10" (25.4cm) cake pan (dark and glass pans aren't recommended). Do not line just the bottom of the pan! Place a full piece of paper over the pan so that the entire thing is lined.

Mix together the honey, coconut oil, maple syrup, vanilla, cinnamon and salt. Stir in the walnuts.

Spread the honey sauce over the bottom of the parchment-lined pan. Place the pan in the refrigerator while you prepare the rest of the cake. This makes it easier to spread the cake batter on top.

In a medium bowl, stir together the flour, baking powder, and salt. Set aside.

In a large mixing bowl, stir together the melted coconut oil, sugar, orange juice, vanilla and eggs. Set aside.

Peel, core and cut the apples into small pieces, about ¼" in size. You can make larger pieces if you like, but it'll make the cake more difficult to cut.

Place them in a bowl and stir in the cinnamon and sugar.

Add the dry cake mixture to the wet and stir just until combined.

Remove the cake pan from the refrigerator and pour half of the cake batter over the honey sauce. It will be a very thin layer. Sprinkle half of the apples (about 1 ½ cups + 2 tablespoons) over the batter. Add the remaining cake batter (again, a very thin layer). It's okay if the apple layer and cake layer blend together a little. Then add the remaining apples. Once it's all done, it won't look like much but it will rise a lot. The reason why I didn't just add the apples to the batter is so that they retain their cinnamon sugar coating. I'd also be worried about the apple pieces interfering with the honey sauce layer.

Bake for 50 minutes or until very lightly browned. The toothpick test does not work here! Once it's lightly browned, you'll have to dig in just a little with a fork or knife to see if it's really done.

Let the cake cool on a cooling rack for 10 minutes before inverting onto the serving plate. The cake will be quite fluffy and therefore a little difficult to get a clean piece when cutting. It'll be easier after about 6-8 hours. After sitting overnight, the cake is a little denser and almost like a coffee cake and much easier to cut.

Cover and store at room temperature for up to 2 days.