Crush the cocoa biscuits into fine crumbs.

Mix the crumbs with the melted butter and milk until the mixture is evenly moistened.

Press the mixture firmly into the base of a 20 cm cake ring or springform pan.

Place in the fridge while preparing the filling and cherry layer.

Add the cherries and sugar to a small saucepan.

Cook over gentle heat, stirring occasionally, until the fruit releases some juice.

Mix the cornstarch with the water in a small bowl.

Pour the cornstarch mixture into the saucepan and stir for about 1 minute, until thickened.

Remove from the heat and let the cherries cool completely.

Divide the cherry mixture into 2 portions.

In a large bowl, whip the mascarpone with the powdered sugar until smooth.

In a separate bowl, whip the cream until thick.

Soak the gelatin sheets in cold water until softened, then melt them gently.

Mix the melted gelatin into the whipped cream.

Fold the whipped cream into the mascarpone mixture until fully combined.

Divide the filling into 2 equal parts.

Stir the Nutella into one half of the filling.

Spread the Nutella cream over the chilled chocolate base.

Spoon over one portion of the cherry mixture and spread gently.

Add the plain mascarpone cream and smooth the top.

Spoon over the remaining cherry mixture.

Refrigerate the cake for at least 4 hours, or overnight, until fully set.

Before serving, cover the top with grated or shaved chocolate.

Slice and serve chilled.