Beat the butter and sugar together in a mixing bowl until light and fluffy. Gradually mix in alternate spoonfuls of beaten egg and flour until all has been added and the mixture is smooth. Stir in the cocoa, orange rind and juice then spoon the mixture into an 18 x 28 cm (7 x 11 inch) roasting tin lined with nonstick baking paper (see
Cut each pear half into long thin slices and fan out slightly but keep together in their original shape. Carefully lift on to the top of the cake and arrange in 2 rows of 4.
Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 30–35 minutes until well risen and the cake springs back when gently pressed with a fingertip.
Lift out of the tin using the lining paper, cut into 8 pieces and peel off the paper. Dust with sifted icing sugar and sprinkle with a little extra grated chocolate and orange rind. Serve warm or cold as it is, or serve it warm as a dessert with ice cream or custard. Store in an airtight tin for up to 2 days.