Put the dates in a small saucepan and pour over 75ml water. Bring to a simmer and cook for 3-4 mins until the dates are mushy and have absorbed the water. Gently stir to blend.
Heat the oven to 180C/160C fan/gas 4. Grease and line the bases of 4 x 150ml pudding moulds. Cream the butter and sugar with an electric whisk until pale and fluffy. Gradually add the eggs and vanilla, then fold in the flour and baking powder. Mix in the blended date puree and divide between the moulds. Transfer to a roasting tin and pour enough boiling water in to reach halfway up the moulds. Cover the tin with foil and cook for 25 mins until risen and firm to the touch.
Meanwhile, make the sauce. Pour half the cream and all the sugar and butter into a small, heavy-bottomed pan. Heat gently until sugar has dissolved, stirring often. Turn up the heat and bubble for 3-4 mins until the sauce is glossy and thick, then stir in the remaining cream. Re-heat the sauce when the puddings are cooked and serve poured on top.