We got a small tub of this last Christmas - the full sized 350g tub costs £6 - and used one heaped teaspoon in hot milk. Although not as spiffy as the Harrods hot chocolate, the Whittards version does make a decent tasting chocolate. It's certainly the better of the lower cost hot chocolate drinks - I prefer the Whittards luxury choc to some of their flavoured chocs.
It can be bought online here Whittards Luxury hot chocolate
It can be bought online here Whittards Luxury hot chocolate