Slow Cooker Creamy Chicken & Mushroom Casserole

Name: Make The PERFECT Creamy Chicken Casserole in Just One Pan!
Prep time: 25 min
Cook time: 6 h
Total time: 6 h 25 min
Yield: 6 servings
Ingredients: 1 kg chicken breast, diced (about 5 breasts); 45 g plain flour, for coating; 0.5 tsp salt; 0.5 tsp black pepper; 2 tbsp vegetable oil, for browning; 2 tbsp unsalted butter; 3 medium onions, peeled and finely diced; 5 cloves garlic cloves, minced; 1 tsp dried thyme; 0.5 tsp celery salt; 25 g plain flour, for the roux; 1 litre chicken stock; 250 ml milk, full fat or half fat; 20 whole chestnut mushrooms, thickly sliced; 0.5 tsp salt; 0.5 tsp black pepper; 2 tbsp lemon juice, about 1 lemon; 240 ml double cream; fresh parsley, chopped

Source video by Kitchen Sanctuary on YouTube. This recipe was adapted with strict source-fidelity rules and is marked for human review.

This creamy chicken and mushroom casserole is the ultimate cosy comfort food. Diced chicken breast is browned and simmered in a thyme-scented sauce of onions, garlic, chicken stock and milk, then finished with double cream for a luscious touch. The original is a one-pan hob recipe from Kitchen Sanctuary's Nikki, but it adapts beautifully to the slow cooker. Serve it spooned over mashed potato with green vegetables and a sprinkle of fresh parsley.

Slow cooker notes: Original is a one-pan hob recipe simmered for around 20 minutes. Adapted for slow cooker: chicken is still browned in flour for colour and flavour, the roux and stock are built in the same pan to avoid lumps, then transferred to the slow cooker. Milk reduced slightly (from 300 ml to 250 ml) because slow cookers retain more liquid and dairy can split over long cooks. Double cream and lemon juice are added in the final 20 to 30 minutes to keep them fresh and prevent splitting. Mushrooms go in from the start as they release liquid slowly.

Ingredients

Chicken

1 kgchicken breast, diced (about 5 breasts)
45 gplain flour, for coating
0.5 tspsalt
0.5 tspblack pepper
2 tbspvegetable oil, for browning

Sauce

2 tbspunsalted butter
3 mediumonions, peeled and finely diced
5 clovesgarlic cloves, minced
1 tspdried thyme
0.5 tspcelery salt
25 gplain flour, for the roux
1 litrechicken stock
250 mlmilk, full fat or half fat
20 wholechestnut mushrooms, thickly sliced
0.5 tspsalt
0.5 tspblack pepper

To finish

2 tbsplemon juice, about 1 lemon (add late)
240 mldouble cream (add late)

To serve

fresh parsley, chopped (add late)

Method

Toss the diced chicken breast with the 45 g of flour, half a teaspoon of salt and half a teaspoon of pepper until evenly coated.
~3 min
Heat 2 tablespoons of oil in a large pan over a high heat. Brown the chicken in 2 to 3 batches, adding an extra splash of oil if needed. The chicken does not need to be cooked through. Transfer to a bowl.
~10 min
Reduce the heat and add 2 tablespoons of butter to the same pan. Add the diced onions, minced garlic, dried thyme and celery salt. Cook for 5 to 10 minutes until the onions are soft.
~8 min
Stir in 25 g of flour and cook for 1 minute. Slowly pour in the chicken stock while whisking to avoid lumps, then whisk in the milk. Bring to a gentle simmer, whisking, until the sauce thickens slightly.
~6 min
Tip the browned chicken and any resting juices into the slow cooker. Add the sliced chestnut mushrooms, then pour over the hot sauce. Season with another half teaspoon of salt and pepper and stir gently.
~3 min
Cover and cook on Low for 6 hours or High for 3 hours, until the chicken is tender and the sauce has thickened.
In the final 20 to 30 minutes, stir in the lemon juice and the double cream (if using). Replace the lid and let it heat through gently. Avoid boiling vigorously to keep the cream from splitting.
~25 min
Taste and adjust seasoning. Serve over mashed potato with green vegetables and a scattering of chopped parsley.
~2 min

Frequently asked

Do I really need to brown the chicken first?

Yes. Slow cookers steam rather than brown, so coating the chicken in seasoned flour and browning it in the pan adds colour, depth of flavour and helps thicken the sauce.

Can I skip making the sauce on the hob?

It is best not to. Building the roux and whisking in the stock and milk on the hob prevents lumps and gives a smooth, glossy sauce. Once thickened, it goes straight into the slow cooker with the chicken.

Why add the cream at the end?

Double cream can split over long, hot cooks. Stirring it in during the final 20 to 30 minutes keeps it silky and fresh tasting.

Can I use chicken thighs instead of breast?

Yes. Boneless, skinless thighs work very well in the slow cooker and stay especially tender. Use the same weight and cook for the same time.

What can I serve with this casserole?

Nikki recommends mashed potato with green vegetables and a scatter of chopped parsley. Rice, crusty bread or buttered noodles also work nicely for soaking up the sauce.

Extraction notes (transparency): Source is a hob one-pan recipe, adapted for slow cooker. Slow cooker timings are inferred from standard practice for diced chicken breast. Milk quantity reduced slightly to account for slow cooker liquid retention. All ingredient quantities are taken directly from the transcript.