Creamy Chicken Mushroom One-Pan Casserole Recipe

Ingredients

Chicken

• 5 chicken breasts (1 kg/2.25 lb) chopped into big chunks or strips
• 45 g (6 tbsp) plain (all-purpose) flour
• ½ tsp salt
• ½ tsp black pepper

Sauce

• 2 tbsp oil
• 2 tbsp unsalted butter
• 3 small-to-medium onions peeled and finely diced
• 5 cloves garlic peeled and minced
• 1 tsp dried thyme
• ½ tsp celery salt (optional)
• 25 g (3 tbsp) plain (all-purpose) flour
• 1 litre (4 1/4 cups) chicken stock
• 300 ml (1 1/4 cups) milk (whole milk or half-fat)
• 2 tbsp freshly squeezed lemon juice (juice of approx. 1 lemon)
• 20 chestnut mushrooms thickly sliced
• ½ tsp salt
• ½ tsp pepper
• 240 ml (1 cup) double (heavy) cream
• 2 tbsp cornflour mixed with 5 tbsp cold water (to make a slurry) – optional
• small bunch parsley chopped

Serve With

• mashed potatoes
• sprouts
• peas
• sweetcorn

Instructions

1. Place the chicken in a bowl with the flour, salt, and pepper. Toss well to coat the chicken evenly with the flour and seasoning.
2. Heat the oil in a large frying pan over high heat. In two batches, add the chicken and brown all over, but do not cook through. Remove chicken with a slotted spoon and set aside.
3. In the same pan, melt butter over low-medium heat. Add diced onions, minced garlic, dried thyme, and optional celery salt. Cook for 5 minutes until onions soften.
4. Sprinkle flour over the softened onions and stir continuously for one minute. The mixture will become lumpy at this point.
5. Pour a splash of chicken stock into the pan and whisk to combine, then gradually add the remaining stock, stirring continuously to avoid lumps, until you have a smooth sauce with onions suspended in it.
6. Add milk and stir over heat until the sauce thickens. Then add the freshly squeezed lemon juice.
7. Stir in the sliced mushrooms, browned chicken, and season with salt and pepper. Cover the pan with a lid and simmer gently on the hob for 20 minutes.
8. Alternatively, transfer the mixture to a casserole dish, cover with foil, and bake in the oven at 175°C/350°F (fan) for 30 minutes.
9. Remove the lid and stir in the double cream. Heat through for another 5 minutes on the hob or in the oven.
10. If desired, stir in the cornflour slurry gradually to thicken the sauce further, adding a little at a time until the preferred consistency is reached.
11. Sprinkle the chopped parsley over the casserole and serve hot with mashed potatoes, sprouts, peas, and sweetcorn.

Notes

• Make Ahead: Prepare the dish in advance, cool, cover and refrigerate for up to 1 day. Reheat covered in the oven at 175°C/350°F for 20-25 minutes or on the hob over medium heat for 10-15 minutes, adding cream or milk if needed to loosen the sauce.
• Freezing: Cool the casserole completely, cover and freeze. Defrost thoroughly in the refrigerator before reheating in the oven covered at 175°C/350°F for 20-25 minutes or on the hob for 10-15 minutes until piping hot.
• Reduce Quantities: You can halve all ingredient quantities without altering cooking times.
• Slow Cooker: The recipe has not been tested in a slow cooker. Feedback on slow cooker adaptations is welcomed for future updates.