Preheat the oven to 200C/400F/gas 6.
Season the partridges inside and out then heat a large stainless steel frying pan or failing that a roasting tray and add the sunflower oil to heat. Roll the partridges in the hot fat and place the birds on their sides and pop into a very hot oven. The birds should take about 13 minutes to roast, a little longer if they are large, shorter of course if smaller. For average sized birds, give them 5 minutes in the oven then remove the pan and turn the birds on to their other sides. Return the birds to the oven for a further five minutes then turn them breast uppermost and roast for a final 3 minutes.
It’s important to turn the birds as they roast, so they pick up a lovely caramelised skin and don’t dry out. Remove the partridges from the oven and transfer to a warm metal tray, setting them breast down to rest after roasting. Keep the birds warm but not too hot or they will carry on cooking.
The sauce can now be made in the same pan as the partridges were cooked in. The birds should rest for at least 10 minutes before serving but I would aim to have them cooked and the sauce made before sitting down to my starter.
For the sauce, peel, core and quarter the apples. Put the pan back on to a low to medium heat and add the rest of the butter and the apples. Sprinkle over the icing sugar and gently fry for three to four minutes until the fruit is browned and glazed.
Now add the chestnuts to the pan. Increase the heat and stir until the chestnuts are coated with the butter from the pan. Add the cider and reduce it until almost disappeared. Add the stock and again reduce, this time by about two thirds. Finish by adding the cream and bringing to the boil. Don’t allow the sauce to over reduce and become too thick. Remove from the heat and set aside.
Remove the legs and breasts from the partridges with a large sharp knife and return to the tray, keeping the rest of the bones for a lovely stock for your freezer.
Heat a clean pan ready to cook the spinach and return the meat back to the oven to warm. Rapidly cook the spinach in the hot pan with a drop of olive oil, salt and pepper. The spinach will wilt in under a minute. When ready tip it out on to kitchen paper to allow any excess liquid to drain off.
To serve, warm the sauce through and season with lemon juice and add two thirds of the chopped chervil. Divide the spinach between four warm plates and spoon the sauce, fruit and chestnuts around the spinach keeping a little sauce back. Set the warm breasts on the spinach and coat with remaining sauce and chervil.