Fish with Parsley Sauce

I've purposely not specified which fish - I used cod but any fish could be used.
Serve with mashed potato/beans etc.

For the parsley sauce, melt some butter in a saucepan. Add flour and cook for a minute.
Add some milk and whisk until smooth.
Add approx 150ml chicken stock.
Add juice of half a lemon.
Whisk til smooth.
Add some double cream, and a handful of chopped parsley.
Keep adding cream until the right consistency.
Season. Serve.