I've made almost the same Debih several times now, it's deeeeeeeeelish
I bought this especially because Nigella used espresso powder and it sounded a good idea:
http://www.ocado.com/webshop/product/Pe ... e/12016011It's such lovely stuff I have a cup a day, but only buy it on offer, which thankfully happens often enough, at £2.69 a jar
It's wonderful for cakes as you just add it to the flour, or to the butter and icing sugar for icing
You can also just make a normal sponge mixture subbing a tablespoon of the powder for one of flour