Preheat the oven to 180ºC/350ºF/gas 4. Season your baby chickens inside and out and stuff each of them with the parsley and tarragon stalks. Using your forefinger, carefully part the skin from the breast meat and smear a teaspoon of wholegrain mustard into each bird. Rub the flour all over the chickens so they are covered in a thin layer. Keep any flour that falls off.
In a snug-fitting casserole-type pan, fry your chickens in 3 good lugs of olive oil on all sides for 10 minutes until golden. Remove them to a plate and then fry off the onion, garlic and celery in the pan. Add the butter and spare flour and continue to fry for about 4 minutes, scraping off any goodness that is on the bottom of the pan. Add your 2 glasses of white wine and allow the liquid to reduce by half, then put the chickens back into the pan. Now pour in your stock – it should come to about half-way up the chickens. Make yourself a cartouche. Wet it so it's flexible then tuck this in and around the pan.
Place in the oven and cook for around 50 minutes to an hour until the chickens have crisp skin and the thigh meat falls off the bone. Remove the chicken to some nice serving bowls – ones that can hold a bit of sauce – and place your pan back on the hob. Add the lettuces, grapes, parsley leaves and tarragon leaves and simmer for a couple more minutes. Correct the seasoning carefully and spoon this sauce next to the chicken.
• from Jamie's Kitchen