In a saucepan, combine water, lemon juice, granulated sugar, and cinnamon. Bring to a boil.

Add apples, then reduce heat and simmer for five minutes. Apples should not be mushy.

Preheat oven to 350 degrees Fahrenheit. Grease a nine x 13-inch baking pan and set aside.

In the bowl of an electric mixer, beat egg whites until stiff peaks form. Add granulated and vanilla sugars and mix to incorporate. Transfer to another bowl and set aside.

In the same electric mixer bowl, combine egg yolks with potato starch, oil, lemon juice, and baking powder. Fold in whites by hand.

Pour batter into prepared pan and bake 50 to 60 minutes. (Leave oven on for the nut garnish below.)

When cake is cool, cut into one-inch cubes.

While the cake cools, combine all nuts on a baking sheet and roast for five minutes. Set aside to cool.

In a large saucepan, mix granulated and vanilla sugars with water. Cook over medium-high heat until sugars dissolve completely. Continue cooking another five to 10 minutes, until golden brown.

Add salt and nuts and mix well to coat completely.

Line the baking sheet with parchment paper. Spread nut mixture on it in a single layer and let cool.

When completely cooled, break into large clusters.

Spoon some apple mixture into the bottom of a dessert glass.

Place a handful of cake cubes over the apples.

Top with a scoop of vanilla ice cream. (The moisture from the apples and ice cream will seep into the cake.)

Top with chopped nuts, grated chocolate, and/or the prepared salted caramel nut garnish.