You will need a large casserole or stock pot to fit your chicken in so that you can cover it with water by about 2.5cm. Stuff the chicken with the parsley and bay leaves, then add your chicken to the pot, cover with water and add a good teaspoon of salt. Scatter in the potatoes, bring to the boil, then turn down, place a lid on top and simmer for about 20 minutes. At this point you can add your baby carrots, turnips or radishes and fennel. Carry on simmering for 30 to 40 minutes.
When you can easily pull the leg bone away from the chicken, you know that it's cooked to perfection. By that time the other veg will certainly be cooked, but don't break them up. Now... while this is all cooking, you can prepare your horseradish cream – the most joyous thing to have with the chicken. In your supermarket you will be able to find creamed or hot grated horseradish in a jar, which is OK to use, but if you're really lucky you'll be able to get hold of some fresh horseradish which you can simply peel and grate, season with salt and mix with the crème fraîche. (I'm lucky because my local supermarket sells them whole – just ask at yours if there are none in stock.)
All you have to do now is carefully remove the chicken to a bowl and add the peas, broad beans and spinach to the broth. Allow them to cook for one minute, then season carefully to taste. You can get all your guests to help themselves if that's easier, but if you want to serve it up, divide a nice mixture of veg between 6 bowls, put some shredded chicken on top, then ladle over some of the wonderful, comforting broth. Sprinkle over some of the chopped reserved fennel tops or some celery leaves, with a healthy dollop of horseradish crème fraîche on top and a drizzle of nice peppery olive oil – it will look and taste brilliant.