Preheat oven to 350°F. Generously grease the inside of a 11 3/4-inch or 12-inch cast-iron skillet with extra virgin coconut oil. Pour the maple syrup into the bottom of the pan. Arrange the apple slices in concentric circles on the bottom of the pan.

In a mixing bowl, whisk together the flour, sucanat or sugar, baking powder, and kosher salt until even. In a separate bowl, whisk together the almond milk, coconut oil, and vanilla extract. Pour into the flour mixture and use a silicone spatula or wooden spoon to stir the two mixtures together until no dry pockets remain. Scoop in dollops over the apples and gently spread toward the edges to level. Bake for 35 to 38 minutes, or until the top has browned a bit and a toothpick inserted in the center comes out clean. Let the cake cool for 10 minutes on the stovetop.

To transfer to a plate or cake stand, run a thin knife or spatula around the inside of the pan. Invert a plate or cake stand that is larger than the circumference of the pan over it. Carefully hold the plate to the pan as you invert the whole shebang. The cake should come out of the pan easily, but if it needs a little encouragement, smack the back of the pan firmly with your hand a couple of times. Carefully remove the pan. The maple syrup will run down the sides of the pan onto the platter. Serve warm, room temperature, or cool. Leftovers can be stored tightly wrapped at room temperature for up to 5 days.