STEP 1 Put the dates in a heatproof bowl, cover with 150ml boiling water, and leave to soak for 30 mins. Butter a 1-litre pudding basin and line the base with baking parchment.
STEP 2 Tip half the butter, half the treacle, the vanilla, 75g of the sugar and the cream into a pan set over a medium heat. Cook for 4-5 mins, stirring, until the sugar dissolves. Turn up the heat, bubble for 3 mins, then whisk in a pinch of salt. Pour a third of the sauce into the basin.
STEP 3 Beat the remaining butter, treacle, sugar and the eggs together, then fold in the flour, bicarb, ¼ tsp salt, the dates and their soaking liquid. Spoon into the basin and smooth the surface, leaving a 1cm gap from the top. Cover with a double layer of baking parchment and foil, making a pleat in the middle so the pud can expand. Secure with kitchen string.
STEP 4 Set the slow cooker to low. Sit the basin inside, then add boiling water so it comes halfway up the basin. Cover and cook for 7-8 hrs. Run a knife around the edge of the pudding and turn out onto a plate. Reheat the remaining sauce and pour over. Serve with ice cream.