This is a decadent rich tart, so serve moderate slices to start with.
What you need
For the base
1 x 23cm loose-bottomed flan tin
300g chocolate biscuits
50g dark chocolate (min. 70% cocoa solids)
60g soft unsalted butter
For the filling
100g dark chocolate (min. 70% cocoa solids)
60ml full-fat milk
500ml pure cream
60g cocoa – sieved
75g caster sugar
1 teaspoon vanilla bean extract
2 teaspoons extra virgin olive oil
½ sea salt
1 punnet fresh raspberries
Icing sugar for dusting
What to do
Roughly break up the chocolate and biscuits and put them in a food processor, then blitz until they turn into crumbs.
Add the butter and blitz again until the mixture starts to form a clump.
Press the mixture into the tart tin and pat down firmly on the sides and bottom, using your hands or the back of a spoon. Press until the base and sides are evenly lined and smooth. Put the tin in the fridge to harden for at least 1 hour.
To make the filling, firstly finely chop the chocolate and place in a bowl.
Put the cornflour into a cup and add the milk then whisk until there are no lumps and the mixture is smooth.
Pour the cream into a medium sized saucepan that will eventually fit all the ingredients. Add the finely chopped chocolate, the sieved cocoa, sugar, vanilla paste, olive oil and salt. Place over a low heat and gently whisk until chocolate has just melted and there are no lumps.
Remove from heat, whisk the cornflour and milk mixture until smooth, then put back on low heat and stir continuously with a wooden spoon until the mixture thickens. You don’t want the cream to boil, so you may need to remove it from the heat to stir from time to time – the process should take about 10 minutes. You will know it’s ready, when the mixture is thick enough to coat the back of a spoon, like custard.
Pour the mixture into a jug. Take a piece of baking paper large enough to cover the jug and run it under cold water – wring it out and place the damp paper right on top so that it touches the mixture – this will stop a skin forming while it cools. Place the jug in the fridge for 15 minutes. You want the mixture to be warm (but not hot) when you pour into the base.
Pour the mixture into the base and refrigerate overnight.
Take the tart out of the fridge 10 minutes before serving. Remove the tart from the tin rest the base on a jar, allowing the allow the ring part to fall away. Place the tart on a platter with the base.
Arrange the raspberries over the top and dust with icing sugar – serve immediately.
TIP: The tart base will go soft after 24 hours in the fridge - not that it is likely to last long anyway.