You will need
Preheat oven temperature to 190C/375F/gas 5.
Whisk all batter ingredients together.
Place macerated rhubarb into a buttered ovenproof serving dish 30cmx23cm/12inx9in. Pour over the batter. Bake in the oven for 30-35 minutes.
When cooked, remove from the oven, dust with icing sugar and serve immediately.