- 125g/4½oz unsalted butter, melted
- 250g/9oz digestive biscuits, crushed
- 4 clementines, juice and finely grated zest
- 225g/8oz unsalted butter, roughly chopped
- 350g/12oz caster sugar
- 4 medium free-range eggs, beaten
- 600ml/1 pint full-fat milk
- 600ml/1 pint double cream
- 1 vanilla pod, seeds removed
- 150g/5½oz caster sugar
- 100g/3½oz cornflour
- 3 medium free-range eggs plus 3 yolks
- 50g/13/4oz unsalted butter, cubed
- 175g/6oz white chocolate, finely chopped
- 2 medium free-range egg yolks
- 2 tbsp caster sugar
- 320ml/11fl oz double cream
- For the base, mix the biscuits and melted butter together in a bowl, then press into a 20cm/8in loose-bottomed tart tin. Cover and chill in the fridge for 20 minutes, or until firm.
- For the clementine curd, put the clementine juice and zest, butter and half the sugar in a saucepan and bring to a gentle simmer to dissolve the sugar and melt the butter, then remove from the heat. Allow to cool slightly. Put the remaining sugar and the beaten eggs in a large bowl and slowly pour in the warm juice mixture, beating constantly using an electric hand-held mixer. Return the pan to the heat and cook over a low heat, stirring constantly, for 5 minutes, or until thickened. Strain through a sieve into a bowl, cover and chill in the fridge until needed.
- For the crème pâtissèrie, put the milk, cream, vanilla seeds and pod into a large heavy-based saucepan and bring to the boil. Put the sugar and cornflour in a large heatproof bowl and whisk in the eggs and yolks. Pour the warm milk mixture over the eggs, whisking constantly. Pour the mixture back into the saucepan and cook gently over a low heat, stirring constantly, until thickened. Pass through a sieve and set aside.
- For the mousse, put the white chocolate in a large bowl and set aside. Whisk together the egg yolks and sugar in a separate bowl until pale in colour. Put 50ml/2fl oz of the cream in a pan and bring to a simmer over a low heat. Slowly pour the hot cream into the egg yolk mixture, stirring constantly. Pour the mixture back into the pan and cook very gently until it coats the back of a wooden spoon. Strain through a fine mesh sieve onto the white chocolate. Stir until smooth.
- In another bowl, whip the remaining cream to almost stiff peaks. Fold half the whipped cream into the white chocolate mixture, then fold in the rest.
- To assemble, combine the clementine curd and crème pâtissèrie and pile into the biscuit base. Spoon the white chocolate mousse over the top, cover and chill in the fridge for at least 2 hours before serving.