This is a chocolate sauce I make - it's quite rich, so a little would go a long way as a 'gravy'!
4 oz dark plain chocolate (I keep it in the fridge and then grate it) either grated or finely chopped
1 oz cocoa powder (not drinking choc powder) mixed to a paste with a tiny amount of cream
4 oz double cream
4 oz unsalted butter, in small cubes at room temp
2 oz brandy/cointreau/rum (or you could leave it out if you don't like alochol)
Bring the cream slowly up to nearly boiling, then pour it onto the chopped/grated chocolate and cocoa paste. Add butter a few lumps at a time and whisk utnil it is all blended together and shiny. Add the alcohol at the end, whisk for a few seconds and then leave to cool.
This will keep in the fridge for a few days.