Preheat your oven to 180°C (fan 160°C) / 350°F / Gas Mark 4. Grease and line your baking dish. Place the chopped dates and bicarbonate of soda into a large bowl, and pour the boiling water over them. Leave to stand for about 15 minutes to soften.

Cream together the butter and sugar until light and fluffy. Beat in the eggs, one at a time, adding a spoonful of flour with each to prevent the mixture from curdling. Fold in the remaining flour, mixed spice, and ginger. Stir in the soaked dates with their liquid and the vanilla extract. Mix until well combined.

Pour the mixture into the prepared baking dish and smooth the top. Bake for 35-40 minutes, or until risen and firm to the touch.

While the sponge is baking, make the toffee sauce: combine the butter, muscovado sugar, and half of the cream in a saucepan. Heat gently until the butter melts and the sugar dissolves, then bring to a boil and simmer for a few minutes until thickened. Remove from the heat and stir in the vanilla extract and the remaining cream.

Once the sponge is cooked, let it cool slightly. Prick the surface all over with a fork, then pour about a third of the sauce over the sponge and let it soak in for a few minutes.

Cut the pudding into squares and serve with the remaining warm sauce poured over, with vanilla ice cream or custard if desired.