Start by making the pastry. Blend 50g cold butter with 100g plain flour until it resembles breadcrumbs. Add 15g caster sugar and 25g chopped, toasted hazelnuts and then bring the pastry together with one small egg. Persevere it will get there in the end but you can add a little cold water if you think it needs it. Wrap the pastry in cling film and chill in the fridge for half an hour. I would recommend making the pastry when you’re as sure as you can be that the phone won’t ring and the doorbell won’t go because otherwise there’ll be pastry all over the place.
Next make the ganache. Put a bowl over a pan of simmering water so that the bowl and water don’t touch. Melt 100g dark chocolate in the bowl, remove from the heat and stir in 150ml of double cream. The mixture should be quite thick and easy to spread over the tart base. Once the tart is done, put it in the fridge to set.
There’s plenty of rhubarb around at the moment and it would be a shame not to use some; it’s pink, it’s seasonal and it makes a fantastic sharp accompaniment to the tart. To make the compote, squeeze the juice of a blood orange into a pan with one stick of chopped rhubarb and a tbsp of sugar. Leave over a low heat to let the rhubarb soften. Once soft, increase the heat until the compote has thickened. In case you’re thinking the last thing you need is some final cooking while your diner waits, it only takes five or ten minutes, it’s minimal effort and you can even ignore it while it’s on the low heat. Don’t forget about it though.