This recipe from The Borough Market Cookbook, written by Ed Smith, is inspired by the many wonderful coffee shops in the market. In his words: 'This dessert is a nod to the busy baristas, with a bold treble hit of espresso underscoring a bitter chocolate filling and cocoa-enriched, shortcrust case.' Since it is a custard-based filling, do be careful when mixing warm cream with the eggs. 

Serves 8-10

Ingredients: Pastry Shell

180g plain flour
150g cold unsalted butter, cubed
30g ground almonds
40g unsweetened cocoa powder
40g icing sugar
Pinch of flaky sea salt
1 egg, lightly beaten
2 tablespoons chilled water

Ingredients: Coffee-Chocolate Filling

200g dark chocolate (85% cocoa solids), broken into chunks
300ml double cream
60ml whole milk
60ml (triple) espresso
3 large eggs
150g golden caster sugar
1/2 teaspoon flaky sea salt

Full-fat crème fraîche, to serve

Method: Pastry Shell

  1. Start by making the pastry base. Rub together the flour and butter until the mix resembles breadcrumbs—you can do this in a bowl with your fingertips or a pastry blender, but it is quicker in a food processor. Add the ground almonds, cocoa powder, icing sugar and salt. Mix or pulse until thoroughly combined, then add half the beaten egg and the chilled water. Bring the pastry together into a ball.
  2. Take the pastry out of the bowl or food processor. Flatten it to form a disc that's 2-3cm thick. Wrap and refrigerate for 1 hour.
  3. After chilling, unwrap the pastry and place it between two large sheets of greaseproof paper. With a rolling pin, roll the pastry out to a thickness of 3mm. Put the pastry back in the fridge for another hour, at least. 
  4. Line a deep, 24cm (9-inch) loose-bottomed tart tin with the chilled pastry. Chill the tin, with the pastry, in the fridge or freezer for 15-20 minutes.
  5. Preheat the oven to 180°C fan/200°C.
  6. Line the chilled pastry base with greaseproof paper. Fill with baking beans or a dried pulse, and bake on the middle shelf of the oven for 10 minutes. Lift the greaseproof paper and its contents from the pastry and bake the pastry for a further 10 minutes.
  7. Reduce the oven temperature to 120°C fan/140°C. Brush the baked pastry case with the remaining half of the beaten egg and place in the cooling oven for 3 minutes—this will help prevent the base from becoming soggy once filled. Remove from the oven and allow to cool completely.

Method: Coffee-Chocolate Filling

  1. Place a heatproof bowl over a saucepan of simmering water, making sure the base of the bowl isn’t touching the water. Add the chocolate to the bowl and leave it to melt without stirring. Remove the pan from the heat once melted and set aside (leaving the bowl over the warm water).
  2. In a separate saucepan, put the cream, milk and coffee and bring to the boil. Then turn off the heat.
  3. Whisk the eggs and the sugar together in a large mixing bowl until light and fluffy. Pour a splash of the hot cream mixture onto the eggs. Beat, then gradually pour the remaining hot cream over the eggs to make a custard. Scrape in the melted chocolate and add the salt. Beat until the custard is smooth and silky (it may seem grainy to begin with but will come together eventually). Cover the filling with a piece of baking parchment, pressing down to make sure it is in full contact, to prevent a skin forming.
  4. Using an oven thermometer or a meat thermometer, make sure the oven has cooled sufficiently to the right temperature for baking the filling (120°C fan/140°C). 
  5. Place the tart tin on a baking sheet, pour the filling into the shell, and bake for 25–35 minutes until it most of the filling is set, with a slight wobble in the very centre. Remove from the oven and leave to cool to room temperature before cutting into portions and serving with crème fraîche.

BK Tips

  • Smith recommends serving the tart in thin slices with a spoon of crème fraîche.
  • Since this recipe takes time and effort (well worth it), we recommend splitting the recipe in half by making the tart shell a day in advance.