Preheat your oven to 180°C/160°C Fan. Grease a large baking dish generously with butter and set aside. Boil your kettle.
Combine the top ingredients together with a whisk- excluding the water and set aside.
Combine all the cake ingredients together and whisk until smooth. This will be quite a thick batter so don't worry. Add to the greased baking dish. Top with the toffee/Caramel or fudge toppings then, using the back of a large spoon, pour over the boiling water.
Carefully transfer to the oven and bake for 35-38 minutes. The top should be lovely and crispy. Serve with cream or ice-cream.
