Whisk together the flour, baking powder, flax meal, sugar, salt, and ½ teaspoon of the cinnamon in a medium bowl.
Beat together the egg whites, coconut milk, coconut oil, and vanilla in a small bowl. Add to the flour mixture and whisk well until combined. Let stand for 30 minutes.
Preheat the oven to 425°F. Coat the bottom and sides of a 10-inch ovenproof skillet with cooking spray.
Combine the organic sugar and remaining ½ teaspoon cinnamon in a small bowl; sprinkle half of the mixture evenly over the bottom and sides of the pan. Arrange the apple slices in the pan in a single layer, in a spoke pattern. Sprinkle the remaining cinnamon mixture over the apples.
Cook over medium heat undisturbed until the mixture bubbles, about 8 minutes.
Carefully pour the batter evenly over the apple slices. Transfer to the oven, being careful not to spill the batter, and bake for 15 minutes.
Reduce the oven temperature to 375°F and bake until the center is set, about 13 minutes.
Cool for 5 minutes, then gently loosen the pancake from the skillet with a spatula and slide onto a serving platter. Alternatively, if you can flip the pancake and plate it with the sliced apples displayed on top.
Sift the confectioners' sugar over the top. Cut into 6 wedges and serve warm.