Tarragon Chicken in a Cream, Onion and Mushroom Sauce

Chicken breasts roasted in an open casserole dish for 40 minutes at 190 deg C, and then another fifteen minutes lidded. With a little sunflower oil. Dressed in some sea salt. Cooked a mixture of julienned white onions (two), plus five destalked and diced chestnut mushrooms, for twenty minutes in sunflower oil.

Decanted the onion and mushroom into a small pan, and mixed with a couple of dessert spoonfuls of single cream, and a shake of dried tarragon. Lots of freshly ground black pepper. 

Served with green beans boiled in salted water for seven minutes.