Preheat your oven to 180ºC/350ºF/gas 4. Put the dates in a bowl with the bicarbonate of soda (baking soda) and cover with 200ml/7fl oz of boiling water. Leave to stand for a couple of minutes to soften, then drain. Whizz the dates in a food processor until you have a purée. Meanwhile, cream your butter and sugar until pale using a wooden spoon, and add the eggs, flour, mixed spice, cinnamon and Ovaltine. Mix together well, then fold in the yogurt and your puréed dates. Pour into a buttered, ovenproof dish and bake in the preheated oven for 35 minutes.

While the pudding is cooking, make the toffee sauce by putting the butter, sugar and cream in a pan over a low heat until the sugar has dissolved and the sauce has thickened and darkened in colour. To serve, spoon out the pudding at the table and pour over the toffee sauce.