Lemon and Spinach Gratin

Roast chicken for two or three always gives sufficient leftovers for another meal and I find it endlessly inspiring. I save leftover gravy too, to add to any sauce I might make. Chicken, young spinach, lemon zest, white wine and plenty of freshly grated nutmeg are a lovely combination held in a Dijon mustard flavoured sauce. I happened to have some leftover mashed potato but not really enough to make a feature of, so it sits under a crisp gratinee finish of Parmesan and breadcrumbs. Lovely. Good with any veg you care you fancy. Chard for me; the stalks separated from the leaves and added to boiling water a few minutes before the leaves.

Serves 2, generously
Prep: 20 min
Cook: 45 min

1 onion
60g butter
150g young spinach
approx 300g roast chicken
approx 4 tbsp leftover mashed potato, optional
1 tbsp flour
1 tsp Dijon mustard
125ml white wine
1 small lemon
150ml chicken stock and/or leftover gravy
3 tbsp finely grated Parmesan
3 tbsp fresh breadcrumbs

Halve, peel and finely chop the onion. Melt 40g butter in a spacious, lidded sauce/frying pan over a medium-low heat and stir in the onion. Stir often as the onion begins to wilt without colouring, cooking for about 15 minutes while you boil a full kettle. Place the spinach in a pan or mixing bowl and cover with the boiling water. Leave for 5 minutes, pushing down with a wooden spoon to immerse, encouraging it to wilt. Drain. Tear or cut the chicken into large bite-size pieces. Season lavishly with salt and pepper. Warm the mashed potato with remaining butter and 2 tbsp milk; it will be almost like a sauce. If the onion is tender, sift the flour over the top, stirring constantly as it mixes into the onion. Stir in the mustard and then the wine, stirring briskly as you add stock and/or leftover gravy. Zest half the lemon with a microplane zester or chop to dust. Stir for a few minutes to cook the flour. Turn off the heat. Press the spinach against the sides of a colander and then squeeze excess liquid with your hands. Slice a few times and stir into the sauce. Now stir in the chicken and lavishly season with nutmeg. Spoon into a gratin dish and leave to set and cool. Spread over the mash. Mix Parmesan and breadcrumbs and spoon it over the top. Spread with the back of a spoon. Place on a baking sheet or similar in case of spillage and bake now or later at 200C/mark 6 for 30 minutes, checking after 20; you want the top crusty and golden. Yum.