1. Add the sugar and 1/4 water to a medium saucepan with a heavy base (this is very important for a temprature) over medium-low heat. Stir until combined. Do Not Stir Again. Only swirl the saucepan until the sugar has melted and turns a medium brown color (if the sugar is too light the sauce will not develop a deep caramel flavour and if it is too dark it quickly burns to become bitter).
2. Add in the granny smith apple, 2-3 tblsp of boiling water and butter and mix until all the butter has melted.
3. Cook on a very low flame, the water will draw water from the apples.
4. When the apples cook down a little, remove the saucepan from the heat and slowly pour in the cream, whisking constantly until all of the cream has been incorporated.
5.Whisk in the sea salt and cinnamon and set aside to cool.
6. Break the Crossiant with your hands into large chunks, heat under a grill till warm. Place is deep plates and pour over the apple caramel sauce.
7. Decorate with a cinnamon stick and the remaining granny smith apple (optional).