Crush the digestives and toss in the butter. Press down on an 8 inch springfoam pan. Leave in the fridge till the filling is prepared.

Preheat oven to 160 degrees. Keep a big pan with boiling water ready.

Whip the cream till stiff. In another bowl, add the remaining ingredients and whip till combined. Fold in the whipping cream. Pour on top of the biscuit base.

Slowly put into the pan with water. Put into the oven and bake for one hour.

Take out and remove the pan. Allow to cool to room temperature.

Chill at least for two hours till set.

Meanwhile, prepare the topping by putting sugar and water into a pan.

Keep swirling till sugar caramelizes and becomes an amber shade.

Drop in the butter. It will splutter, so stay away. Once the butter is incorporated, add the cream. Keep till warm and switch off.

Add the chocolate over the hot mixture and leave undistubed for a couple of minutes. Fold with a spatula till all melted. Allow it to cool completely.

Spread on top of the set cake. You may allow the ganache to set or serve immediately.