For the pear and walnut tart, preheat the oven to 200C/400F/Gas 6.
Place the flour and butter into a blender or food processor and blend until the mixture resembles breadcrumbs.
Add the egg and milk and blend until it forms a ball. Turn out onto a flat surface, knead into a ball and then roll to the thickness of a pound coin.
Cut out a 20cm/10in rectangle, prick with a fork, top with the sliced pear and sprinkle over half the sugar.
Slide onto a baking sheet and bake for five minutes. Add the rest of the sugar and the walnuts and bake for another three minutes, or until the pastry is golden. Remove from the oven and place onto a large serving plate.
For the chocolate sauce, whisk together the cream, cocoa powder and icing sugar in a small saucepan over a low heat until well combined.
To serve, cut a slice of the tart, pour over the double cream and drizzle with plenty of chocolate sauce.