Well I tested the new stove-top oven with some 'biscuits', and they cooked exactly the same as they did in the old one. Which isn't very surprising as they are virtually identical.
And then we decided to test it on the cook-top of the rocket-mass-heater.
We suspected it wouldn't work as well as on a gas flame as the funnel thing is designed to capture the gas flame and shoot the heat up into the oven and away from the bottom of the pan. Or it might turn out that the hot surface of the stove top will make the bottom of the pan overheat anyway. But we figured there was only one way to find out, so I made up a batch of biscuit dough while Austin lit the rocket mass heater up and we had a go...
We put the funnel on the hottest bit of the stove and popped the stove-top oven on top.
The base of the pan doesn't directly contact the stove-top so in theory the biscuits won't burn on the bottom.
The stove top was nice and hot but it seemed to take the oven much longer than usual to warm up. When I was convinced it wasn't going to burn, we left it to do it's thing and checked it thirty minutes later. Then another thirty minutes.
And finally after an hour and half we got hungry enough to declare them to be cooked.
They didn't brown properly, and were just a touch doughy inside, but good enough.
So we had wheat-and-flaxseed biscuity roll things for tea, slathered in butter!
And they were delicious!
So, the verdict. The stove-top cooker does work on the stove-top of the rocket mass heater, but only just. If I was lighting it in the summer because it was our only cooking option I would choose another way to cook the biscuits, probably in a cast iron skillet. At this time of year though when it's running for a few hours a day anyway, it would be an easy option to light it, quickly put some biscuits in the stove-top oven and leave it on there for about two hours and eat them when they're ready.
We could experiment taking some of those discs out so the funnel fits directly over the hot gasses rather than the hot cast iron stove top, but it might spoil the draught of the stove. We must might experiment with that in the future. Not sure yet...