Preheat the oven to 200°C / 180°C (fan oven) / 395°F / Gas Mark 6. Arrange the chicken breasts in a single layer on a baking tray, cover with foil and bake for 25 minutes until completely defrosted and starting to cook. Pierce the thickest part of each breast with a knife to check there's no resistance or ice crystals.

Meanwhile, heat the oil over a high heat, in a large frying pan. Add the mushrooms and fry for 5 minutes until all the water has evaporated. Lower the heat to medium-high, add the garlic and cook for another minute. Pour in the wine, if using, and simmer for 2-3 minutes. Add the chicken breasts and frozen spinach and cook for 5 minutes, then pour in the cream and stock and simmer gently for 15 minutes, turning everything over every few minutes until the chicken is cooked through, the spinach is defrosted and the sauce coats the back of a spoon.

Stir through the cheese and season to taste. Remove from the heat and serve with mashed potatoes and green beans, if you like.