Preheat oven to 375 degrees Fahrenheit. Grease the ends of a nine-inch loaf pan with oil. Line the bottom and two long sides of the pan with a piece of Gefen Parchment Paper. Place the loaf pan on a sheet pan, to catch any drips.

Peel and core your apples. Use a mandoline to slice apples very thin, about 1/8-inch thick. Place apples in a large bowl and gently toss with lemon juice.

Using a whisk, combine eggs, sugar and salt. Add oil and vanilla, if using. Whisk in potato starch and apple juice until smooth. Pour batter over sliced apples, then turn the apples over a few times to evenly coat.

Set aside a dozen nice slices for the top layer. Arrange the remaining apple slices slightly overlapped around the prepared loaf pan, pushing the straight edges against the sides for the neatest appearance. Use any smaller or broken apples to fill any center gaps. Tap the pan on the counter a few times to release any trapped air bubbles. Use the reserved apple slices to decorate the top, arranging them in a flower pattern.

Bake for 60 to 70 minutes, or until a toothpick or skewer inserted into the center of the cake slides into the apples easily and comes out batter free.

Transfer to a cooling rack for five minutes, then brush top with honey or sugar water and let cool completely in the pan. The cake will be puffed at first, and will settle as it cools.

Once it has cooled to room temperature, loosen the cake from the ends of the pan. Use the parchment paper overhang to help lift it out of the pan, loosening the ends with a knife, if necessary. Remove parchment paper and transfer to a serving plate. Cut into slices.