Method

1. For the pastry, put flour and icing sugar in a large bowl and rub in the butter with your fingertips until the mixture resembles fine breadcrumbs.

2. Add the egg yolk and water and mix until it comes together to form a firm dough. Wrap in cling film and leave to rest in the fridge for about 30 minutes.

3. Preheat the oven to 200C/400F/Gas 6 (180C fan). Dust the work surface with flour and then roll out the pastry as thinly as you can to a circle - about 5cm/2in larger than your flan tin. Line the tin with pastry. Don’t worry if the pastry breaks a little, it is easy to patch up. Leave to chill in the fridge for 15 minutes.

4. Prick the base of the pastry with a fork and line the pastry case with a circle of baking parchment or foil and fill with baking beans. Bake the pastry blind for 10 minutes, or until just lightly golden-brown, then remove the paper and beans and return the tart to the oven to cook for a further 5-7 minutes, or until pale golden-brown and dried out.

5. For the filling, melt the butter in a medium pan over a low heat, then add the chocolate and stir until melted and smooth. Remove from the heat and stir in the sugar and flour. Beat in the eggs, one at a time.

6. Place the pastry case on a baking tray. Pour the mixture into the pastry case, filling it right to the top and place in the oven. Bake for 10-12 minutes, or until just set around the edges - but it should still be slightly wobbly in the centre.

7. Remove from the oven and allow to cool. Dust with icing sugar - if liked, you can cut a heart shape out of baking parchment and place on top of the tart before dusting with icing sugar, then remove the paper to make a stenciled effect. Or serve warm with strawberries, a dusting of icing sugar and cream.