Pack the chicken thighs into the base of a saucepan, add the wine, stock, thyme and a little seasoning. Bring to the boil, then cover and simmer for 45 minutes until tender.
Meanwhile, heat the oil in a frying pan, add the onions and fry for 5 minutes until just turning golden. Mix in the garlic and cook for 2–3 minutes, then stir in the mushrooms and fry for 2–3 minutes until golden.
Lift the chicken out of the pan, drain and set aside. Pour the stock into a measuring jug. Make up to 600 ml (1 pint) with water if needed. Wash and dry the pan, then melt the butter in it. Stir in the flour, then gradually whisk in the stock and bring to the boil, stirring until thickened and smooth. Stir in the cream and adjust the seasoning, if needed.
Soak the lasagne sheets in boiling water for 5 minutes. Cut the skin and bones away from the chicken and dice the meat. Drain the lasagne sheets.
Pour a thin layer of sauce into the base of a 20 x 28 x 5 cm (8 x 11 x 2 inch) ovenproof dish or roasting tin, then cover with 2 sheets of the lasagne. Spoon over half the mushroom mixture and half the chicken, then cover with a thin layer of sauce. Repeat the layers, then cover with the remaining lasagne and sauce. Sprinkle with the Parmesan and set aside until required.
Cook in a preheated oven, 190°C (375°F), Gas Mark 5, for 40 minutes until piping hot and the top is golden. Serve with salad and garlic bread.