Preheat oven to 180 degrees C / 350 degrees F (fan).
Wash, trim and chop the rhubarb into approx 2 cm pieces and place in an oven dish. Sprinkle over the sugar.
600 g rhubarb, 100 g caster sugar (superfine sugar)
Cream the butter and sugar for the sponge topping together in a bowl.
110 g caster sugar (superfine sugar), 110 g butter
Add the eggs, flour, baking powder and vanilla extract and beat well.Your mixture should be spoonable and not too runny. 2 medium eggs, 110 g self-raising flour, 1 tsp baking powder, 1 tsp vanilla extract
Spoon the sponge mix over the prepared rhubarb. Don’t worry too much about covering all the fruit, the sponge will spread as it bakes.
Bake for 35-40 minutes until golden brown and risen.
Dust with icing sugar if desired. Serve warm with custard, cream or ice cream.