I keep tripping over recipes for a "whole orange cake". There are a few different ones around, but basically, you throw all ingredients together, including a whole orange, chop/mix it up, pop it in the oven, and that's it.
I'll admit to wondering it something that easy can be that good? And yep, it is. Especially straight out of the oven. The only alteration I made was to use gluten free flour, and the cooking time depends on the size and juiciness of the orange. Next time I'll try adding poppyseeds!