This is a delightfully retro chocolate biscuit refrigerator cake. You could add some glace cherries or raisins for a bit of variety, but it's quite lovely as it is. Don't worry too much about the size of the tin. As you can see from my mistake with a too big tin, it holds it shape well.
These look nice cut into cake-shaped slices, but if you only had a square tray you could cut them like a tray bake too
Preparation Time: 10 minutes
Cooking Time: 20 minutes
Makes: 6-8 servings (more if you slice into smaller, thinner wedges)