Description

This Creamy Chicken and Mushroom One Pan Casserole is a comforting and hearty dish that features tender chicken breasts and sautéed mushrooms simmered in a rich, creamy sauce infused with garlic, onions, thyme, and a hint of lemon. Perfect for an easy weeknight dinner, this casserole is cooked on the stovetop or can be finished in the oven, and is best served with classic sides like mashed potatoes, peas, sprouts, and sweetcorn.

Ingredients

Scale

Chicken and Coating

5 chicken breasts (1kg/2.25 lb), chopped into big chunks or strips
45 g (6 tbsp) plain (all-purpose) flour
1/2 tsp salt
1/2 tsp black pepper

Sauce Base

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
1/2 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)

Mushrooms and Finishing

20 chestnut mushrooms, thickly sliced
1/2 tsp salt
1/2 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

To Serve

Mashed potatoes
Sprouts
Peas
Sweetcorn

Instructions

Coat the Chicken: Place the chopped chicken breasts in a bowl with 45 g flour, 1/2 tsp salt, and 1/2 tsp black pepper. Toss well to evenly coat all pieces in the flour mixture.
Brown the Chicken: Heat 2 tbsp oil in a large frying pan or skillet over high heat. Working in two batches, add the chicken pieces and brown them on all sides. The chicken doesn’t need to be fully cooked at this stage. Remove browned chicken with a slotted spoon and set aside.
Sauté Aromatics: In the same pan, melt 2 tbsp unsalted butter over low-medium heat. Add the diced onions, minced garlic, 1 tsp dried thyme, and 1/2 tsp celery salt if using. Cook and stir occasionally for about 5 minutes until the onions soften.
Create the Sauce Base: Sprinkle 25 g flour over the softened onions and stir for about a minute to coat and cook the flour, although it may look lumpy. Gradually pour in a splash of the 1 litre chicken stock, whisking continuously to combine. Continue adding the stock a little at a time while whisking to create a smooth sauce without lumps, though the onions will remain visible.
Finish the Sauce: Stir in 300 ml milk and cook over heat, stirring until the sauce thickens. Then add the freshly squeezed lemon juice to brighten the flavor.
Add Mushrooms and Simmer: Mix in the sliced mushrooms, browned chicken, and season with 1/2 tsp salt and 1/2 tsp pepper. Cover with a lid and simmer gently on the stovetop for 20 minutes to allow flavors to meld and chicken to finish cooking.
Oven Alternative: Alternatively, transfer the mixture to a casserole dish, cover with foil, and bake in a preheated oven at 175°C (350°F fan) for 30 minutes to complete the cooking.
Incorporate Cream: Remove the lid (or foil if oven cooking) and stir in 240 ml double cream. Heat through for another 5 minutes on the stovetop or in the oven.
Adjust Sauce Thickness (Optional): If desired, add the cornflour slurry a little at a time while stirring until the sauce reaches your preferred thickness.
Serve: Spoon the creamy chicken and mushroom casserole onto plates and serve with mashed potatoes, sprouts, peas, sweetcorn, and a sprinkle of chopped parsley for garnish.

Notes

For a thicker sauce, use the optional cornflour slurry.
Can be cooked entirely on the stovetop or finished in the oven for ease and convenience.
Chestnut mushrooms can be substituted with cremini or button mushrooms if preferred.
Adjust seasoning according to taste, especially if using lower-sodium chicken stock.
Serving with classic vegetable sides adds color and nutrition to the meal.

Prep Time: 15 minutes
Cook Time: 30 minutes
Category: Dinner
Method: Stovetop
Cuisine: British

Keywords: chicken casserole, mushroom casserole, creamy chicken recipe, one pan dinner, easy comfort food, stovetop casserole