When I returned to the kitchen, the rhubarb had transformed into that familiar soft stringy pulp. While I reheated some of my weird stew for dinner, I mixed up the sponge batter to put on top. It's simple really - cream butter, sugar and vanilla essence, then beat in eggs and add sifted dry ingredients. In a very short time, the sponge topping was spooned onto the rhubarb and placed in the oven.
40 minutes later, I pulled out a perfect-looking sponge with traces of rhubarb peeking out around the edges. When I spooned out a portion, I found it was still pretty gooey in the centre, but I put the lid back on and the trapped heat had cooked the rest by the time I looked at it again.
I thought the leftovers would go soggy overnight, but actually it reheated quite nicely the next day, with only the slightest sogginess. The sponge was beginning to dry out though - this would have been a good time to try the custard, come to think of it!
So all in all, a pretty good recipe really - another option for a tasty fruit-based dessert if you're getting sick of the usual crumble.