In a bowl of your electric or hand mixer whip the egg, granulated sugar and lemon zest until pale and fluffy.
Using a spatula, gently stir in the heavy cream, sift in the flours, baking powder and mix. Add the oil and gently mix until combined.
Pour the batter in the cake ring (16cm) and bake at 170°C(338°F) for 12-15min or until slightly risen and golden. Put aside until completely cooled. Cut the biscuit in half lengthwise, you will only use one half for this dessert. Wrap and freeze the other half for other desserts.
Making the apple jelly:Soak gelatin in cold water.
Wrap a 14cm cake ring in plastic foil, to prevent leaking. Place it on a baking tray.
Peal and cut the apples in small cubes.
Put sugar and butter in a pan and melt on medium heat. Add diced apples. Add the spices and lemon juice. Cook apples until soft. Take off the heat and stir in the soaked gelatin.
Set a side to cool. Pour the mixture in the prepared cake ring.
Freeze the apple jelly for a couple hours or overnight, until completely frozen.
Making the caramel mousse:Soak gelatin in cold water.
Pour heavy cream(115g) in a small pot and heat on medium heat. Meanwhile make a dry caramel by putting the sugar in a small pot. Cook until it melts completely and turns dark amber. Turn off the heat and add butter and warm cream into the caramel, place back on low heat and stir constantly until smooth. It will bubble so be careful. Take off the heat.
Add the soaked gelatin to the caramel mixture and stir to combine. Pour in a clean bowl and set aside to cool completely.
Whip the remaining heavy cream to soft peaks. Gently fold into the caramel mixture until completely combined. Add salt to taste.
Wrap a 18cm cake ring in plastic wrap, to prevent leaking. Pour in 1/2 of the caramel mousse. Place in the freezer to set slightly.
Unmold the frozen apple jelly and place gently on top of the caramel mousse.
Pour over the remaining mousse. Gently place the lemon biscuit on top and push down slightly. Cover with foil and place the cake back in the freezer overnight.
Making the caramel glaze:Soak gelatin in cold water. Chop chocolate in small pieces and set aside.
Place sugar, water and glucose in a medium sized pot. Cook on medium heat until amber. Meanwhile heat heavy cream until hot, set aside.
Once the sugar is hot enough pour in the hot cream slowly. Stir and pour over the chopped chocolate. Add the soaked gelatin. Stir and using the immersion blender whiz until completely smooth. Set aside to cool down.
Assembly:Take the cake out of the freezer. Using a blowtorch, heat the sides of the cake ring. The cake should go out easily.
Place it over a wire rack over a large bowl. Pour the cooled caramel glaze over the cake, taking care you cover the sides.
Tap the rack gently to remove excess glaze. transfer the cake on your stand and garnish with caramel popcorn, chocolate, fresh apple and whipped cream. Place it in the fridge to thaw completely before serving. Enjoy!