Don't dismiss this too lightly without trying it.  It's just the thing to pour over your roast dinner and  mashed potatoes. 

• pour off  the flavouring from the roast into a saucepan

• place an envelope of dried onion and mushroom soup into it

• add a can of pepsi (yes! you heard right)

• add a can of cream and mushroom soup

• add corn starch to thicken it up

• whisk and there you have it!

Best of luck