1. Preheat oven to 350 degrees F. For cake, sift together the dry ingredients and mix. Create a well in the center and fill with wet ingredients. Mix until just combined.
2. Transfer 1/2 the batter to a loaf tin. Distribute the jam filling over the batter. Top with the remaining batter.
3. For crumble topping, using your fingers, mix dry ingredients and rub the vegan butter into the dry ingredients until a crumbly consistency is reached.
4. Take 1/2 the crumble mixture and place it on top of the cake mixture, pressing it in slightly. Add the remaining crumble mixture. Transfer to oven and bake until firm, about 30-40 minutes.
My oven is seriously shiitake, and so it took about 2 hours in there. If you have a good working oven, keep an eye on it!
Source of recipe: I stewed some rhubarb, not knowing that you didn't need water, so I had a big pot of soupy stewed rhubarb which I was not willing to let go to waste. Thus, this cake was born.