After Eights chocolate tart

Method

1. Sift the flour, icing sugar, cocoa and salt together into a large bowl. Rub the butter into the dry ingredients until the mix resembles fine breadcrumbs. Add the egg yolks and 2 tbsp ice-cold water, then quickly mix until a soft dough forms, adding another 1 tbsp water only if needed (don’t overwork it). Alternatively, pulse the dry ingredients in a food processor with the butter, then add the yolks and water, pulsing again until the dough comes together. Wrap the dough in baking paper and chill for at least 1 hour.
2. Roll out the dough between 2 pieces of baking paper to the thickness of a £1 coin, then use it to line the tart tin, pressing it up the side and leaving some overhanging. Cover and chill for another hour.
3. Heat the oven to 170ºC fan/gas 5. Prick the pastry base a few times with a fork, then line with baking paper and fill with baking beans or uncooked rice. Bake for 20 minutes, then remove the beans/rice and paper and bake for 15 20 minutes until the pastry feels sandy to the touch. Leave to cool completely, then use a sharp knife to trim away the excess pastry.
4. To make the white chocolate ganache, melt the chocolate and cream in a heatproof bowl set over a pan of simmering water, making sure the bowl doesn’t touch the water. Remove from the heat, stir in the peppermint, then leave to cool for 15 minutes. Pour into the tart case, then chill again for 1 hour.
5. For the dark chocolate layer, melt the chocolate, cream and sugar in a heatproof bowl set over a pan of barely simmering water as before, stirring until the chocolate is melted and the sugar dissolved. Remove from the heat and leave to cool for 15 minutes, then pour on top of the white chocolate layer in the tart. Arrange the After Eights in a tile pattern on top, then chill for 4 hours or until set completely. When ready to serve, carefully remove the tart from the tin. Dust with cocoa and slice.