Use your favourite marmalade here – one with a decent, grown-up bitterness. If it’s very thick-cut, chop the pieces of peel roughly so that it spreads easily.
The pastry recipe makes enough for two 24cm tarts, but is difficult to make in a smaller quantity. You can chill or freeze the second half of the pastry to use another time. Use a tin with a loose base so you can remove the tart easily before serving.
For the tart shell:
150g butter, at room temperature
65g plain flour
95g icing sugar
35g ground almonds
½ tsp fine sea salt
190g plain flour
In the bowl of a stand mixer, beat the butter until light and creamy. Scrape down the bowl, then add 65g of the flour, the icing sugar, the almonds, the egg and the salt. Mix at medium speed until a soft paste forms, then scrape down the bowl. Add the rest of the flour and mix until just combined. Wrap in cling film and chill for at least an hour before using, or for up to three days.
To form the tart shell, lightly flour your work surface and roll the pastry out to a 3mm disc, just slightly larger than the tart tin. Carefully wrap the pastry disc around the rolling pin. Sit the tin right in front of you, then lift the rolling pin over it and allow the pastry to unroll neatly in.
Press the pastry gently down into the base of the tin, making a neat, sharp angle between the sides and the base of the tin, but don’t push or stretch it too much. Gently press the pastry evenly up the sides of the tin, then use the blunt edge of a knife to trim neatly all around the top. The pastry should be exactly level or almost imperceptibly higher than the tin. Chill for at least 30 minutes. Meanwhile, preheat your oven to 180C.
Line the pastry case with heavy aluminium foil or baking paper and fill it with baking beans.
Bake for 15-20 minutes until cooked through – peek under the foil to check that the outer edge is done. The centre won’t be quite ready yet. Take out the oven, allow to cool until you can handle it, then carefully remove the weights and foil. Return to the oven and bake for 10 minutes more, until the pastry is an even golden colour in the centre, and cooked right through.
Allow to cool completely before filling.
For the filling:
300g dark chocolate, chopped
200g butter, at room temperature, diced
2 medium eggs
2 medium egg yolks
50g soft brown sugar
¼ tsp fine sea salt
Combine the chocolate and the butter in a heatproof bowl and sit the bowl over a saucepan of gently simmering water, stirring regularly until they melt smoothly together. Set side to cool slightly. Meanwhile, combine the eggs, yolks, sugar and salt in the bowl of a stand mixer and use the balloon whisk attachment to whisk together until very pale and tripled in volume – this will take around 10 minutes.
With a large metal spoon, mix a third of the chocolate mixture into the whisked egg mixture – no need to be too careful about this – then fold in the remaining chocolate very gently and carefully.
Spread the marmalade evenly over the base of the tart shell and slowly pour over the chocolate filling, allowing it to settle and reach its own level.
Bake for 15 minutes, until just set. The edges of the filling will rise and then crack a little, and the centre should still have a slight wobble to it.
Leave to cool completely before serving, with a dollop of crème fraîche and a teaspoon more marmalade.