I, too, have been guilty of discovering a shrivelled aubergine in the bottom of the fridge, and I think I improved on the recipe a bit.
First I softened the onion in butter, then I added the crushed garlic, the aubergine peeled and diced, and the cumin seeds. I let them all roast in the pan for a while, until the aubergines took some colour, then I added the stock. Carefully, as the pan with the roasting aubergines is far above 100°C and the first splash of water turns into steam very quickly.
When it was all soft and yummy, I added two spoonfuls of tahini, as a thickener, a generous grating of nutmeg, and blended the lot.
What came out is basically a soup version of baba ganoush, and it is yummy!