Why You’ll Love Creamy Chicken and Mushroom One‑Pan Casserole Recipe

Because it uses one pan (or one large casserole dish), meaning fewer pots to wash and less fuss.
The sauce is indulgent yet homey – milk, cream and chicken stock combine for a truly comforting flavour.
It’s made in a batch (serves about 10) so you can enjoy some now and freeze the rest for later.
You can cook it on the hob or transfer to the oven depending on what suits you.
Works beautifully served over mashed potatoes, with peas, sprouts or other green vegetables to balance the richness.

Ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

Chicken:
Chicken breasts, chopped into big chunks or strips
Plain (all‑purpose) flour
Salt
Black pepper

Sauce:
Oil
Unsalted butter
Onions, finely diced
Garlic cloves, minced
Dried thyme
Celery salt (optional)
Plain flour
Chicken stock
Milk (whole or half‑fat)
Fresh lemon juice
Chestnut mushrooms, thickly sliced
Salt & pepper
Double (heavy) cream
Cornflour (cornstarch) mixed with cold water (optional, for thicker sauce)
Fresh parsley, chopped

To serve with:
Mashed potatoes
Sprouts, peas, sweetcorn

Directions

Place the chicken in a bowl with the flour, salt and pepper. Toss to coat the chicken evenly.
Heat the oil in a large frying pan (or suitable large casserole pan) over high heat. In two batches, add the chicken and brown all over (it doesn’t need to be cooked through fully). Remove the browned chicken from the pan and set aside.
In the same pan, melt the butter over low‑medium heat. Add the onions, garlic, dried thyme and (if using) celery salt. Cook for about 5 minutes until the onions soften. Then sprinkle the flour over the mixture and stir for about 1 minute (it may become a little lumpy).
Pour in a splash of the chicken stock and whisk until smooth. Gradually add the rest of the stock while stirring until you have a smooth sauce.
Add the milk and continue stirring until the sauce begins to thicken. Stir in the lemon juice.
Return the cooked chicken and mushrooms to the pan, and season with salt and pepper. Cover with a lid and simmer on the hob for about 20 minutes. (Alternatively, transfer to a casserole dish, cover with foil and bake at 175°C (350°F fan) for 30 minutes.)
Remove the lid, pour in the double cream and heat through for 5 more minutes. If desired, add cornflour slurry to thicken the sauce further.
Stir in the chopped parsley and serve immediately with mashed potatoes and vegetables.

Servings and timing

Servings: 10 portions
Prep time: Approximately 15 minutes
Cook time: Approximately 50 minutes
Total time: About 1 hour and 5 minutes

Variations

Use boneless, skinless chicken thighs instead of breasts for a richer flavour and more moist texture.
Swap the chestnut mushrooms for a mix like button, shiitake or cremini for deeper umami.
Add chopped bacon or pancetta for a smoky twist.
Stir in spinach or kale in the last 5 minutes for extra greens.
Use half cream and half milk to lighten the dish.
Add a splash of white wine after browning the chicken for added depth.
Use fresh thyme or chives instead of parsley for a different herb finish.

Storage/Reheating

To store: Allow to cool, then cover and refrigerate for up to 1 day.
To freeze: Cool completely, transfer to a freezer-safe container, and freeze.
To reheat from fridge: Reheat covered in the oven at 175°C (350°F fan) for 20–25 minutes or warm on the hob for 10–15 minutes, adding a splash of cream or milk if needed.
To reheat from frozen: Defrost overnight in the fridge, then reheat as above.

FAQs

What mushrooms work best in this casserole?

Chestnut mushrooms are ideal, but button, cremini or shiitake can also work well.

Can I make this dish ahead of time?

Yes, it can be cooked in advance, cooled, and refrigerated for up to one day before reheating.

Is it possible to make this in a slow cooker?

It hasn’t been tested in a slow cooker, but it could be adapted using low heat and checking that the chicken is fully cooked.

Can I reduce the batch size if I only need 4–5 portions?

Yes, halve the quantities; cooking time remains the same.

What should I serve with the casserole?

Mashed potatoes, steamed peas, sprouts, or other green vegetables pair perfectly with the creamy sauce.

How can I thicken the sauce if it’s too thin?

Add a cornflour slurry (cornflour mixed with cold water) a little at a time while stirring.

Can I use a lighter cream or milk alternative?

Yes, substitute part of the double cream with lighter cream or use whole milk for a lighter sauce.

What about seasoning—should I adjust anything?

Taste before serving and adjust salt and pepper, especially if serving with salty sides.

Can I add vegetables into the casserole?

Yes, chopped carrots, bell peppers, green beans, or spinach can be added — just adjust cooking time as needed.

Is it safe to freeze this dish with the cream in it?

Yes, it freezes well. Defrost fully before reheating, and stir in a little milk or cream if the sauce thickens too much.

Conclusion

This creamy chicken and mushroom one-pan casserole is a family-friendly favorite that delivers both comfort and convenience. With its rich sauce, tender chicken, and flexibility in preparation and storage, it’s the perfect make-ahead meal or hearty weeknight dinner. Serve it up hot with your favorite sides and enjoy every spoonful.