Put the dates, raisins, rum and 100ml water in a small saucepan and set over a low heat until steaming, about 5 mins (or do this in the microwave). Leave to cool.

Meanwhile, make the toffee sauce. Put all the ingredients except the cream in a small pan and bring to a simmer. Cook until the sugar has dissolved and the sauce is glossy, about 5 mins. Pour in the cream and cook for 2 mins more, stirring continuously, then remove from the heat and set aside. The sauce will continue to thicken as it cools.

Generously butter a 1.5-litre pudding basin. Beat the butter and sugar until well combined in a large bowl using an electric whisk, or in a stand mixer. Add the eggs one at a time, beating well between each addition. Fold in the flour, spices and the soaked fruit until evenly incorporated, then stir in the milk.

Pour a quarter of the toffee sauce into the base of the prepared basin, then spoon in the sponge batter. Place a sheet of baking parchment over a sheet of foil, then make a pleat in the centre. Use this to cover the pudding, parchment-side down, and tie securely under the lip of the basin using kitchen string.

Transfer the basin to a steamer. Alternatively, put an upturned plate in the base of a large pan, sit the basin on top, and half-fill the pan with water from the kettle so it goes halfway up the side of the basin. Cover and cook over a low heat for 2 hrs 35 mins, checking the water level every so often and topping up when needed.

Check the sponge is ready by inserting a skewer into the middle. If it comes out clean, the sponge is cooked. If any uncooked batter clings to the skewer, continue steaming, then check again after about 20 mins.

To serve, warm the remaining toffee sauce over a low heat, invert the sponge onto a serving plate, and pour over the warmed sauce. Serve with custard or ice cream.