Prepare the Chicken: In a medium bowl, combine the plain flour, salt, and pepper. Add the chicken thigh chunks and toss well until each piece is lightly coated. This flour coating will help to thicken the stew later on.

Brown the Chicken: Heat the olive oil in a large, heavy-based frying pan or casserole dish over a medium-high heat. Add the chicken in two batches, being careful not to overcrowd the pan. Cook for 3-4 minutes on each side, until golden brown. You don't need to cook it through. Transfer the browned chicken to your slow cooker pot.

Sauté the Vegetables: Lower the heat to medium and add the chopped onions, carrots, and celery to the same pan. Cook for 6-8 minutes, stirring occasionally, until they begin to soften and the onion is translucent. Add the minced garlic and cook for one more minute until fragrant.

Deglaze the Pan: If using, pour the white wine into the pan. Use a wooden spoon to scrape all those tasty browned bits from the bottom – this is where so much flavour lies! Let the wine bubble and reduce by about half. If you're not using wine, simply use about 100ml of your chicken stock for this step.

Combine in the Slow Cooker: Transfer the cooked vegetables to the slow cooker with the chicken. Add the chopped potatoes, tomato purée, Worcestershire sauce, thyme, and bay leaves. Pour over the hot chicken stock and stir everything together gently.

Cook Low and Slow: Secure the lid on your slow cooker. Cook on LOW for 6-8 hours or on HIGH for 3-4 hours. The stew is ready when the potatoes and carrots are tender and the chicken is cooked through and succulent.

Final Touches: Remove the bay leaves before serving. Taste the stew and adjust the seasoning with more salt and pepper if needed. If you'd like a thicker gravy, you can make a slurry by mixing 1 tablespoon of cornflour with 2 tablespoons of cold water, stir it into the stew, and cook on HIGH for another 15-20 minutes with the lid off.

Serve: Stir through the chopped fresh parsley and ladle the hot stew into bowls.