Help now please! How to make gravy without pan juices??

[BR44]

Roasted a chicken this morning and stupidly didn't keep any of the lovely pan juices. How can I make a sauce to go with the reheated chicken and roast veg tonight? I'm guessing some combo of roux and stock but it sounds a bit heavy. I don't have any white wine in annoyingly. Anyone?

gravy granules - the clue's in the name

Haven't got any!

Fry off half a finely chopped onion, crumble in a stock cube, fry a little longer, then pour in about half a pint of water. Bring to the boil, then turn the heat right down and whisk in 50ml more water mixed with 1-2 tsp of cornflour, depending on how thick you like your gravy. Season and keep warm