Slice the chicken in half lengthways to give 4 thinner fillets.
Tip the flour into a dish or a plate, then add the salt and pepper and mix well. Coat the chicken in the seasoned flour.
Heat some oil in a large frying pan over a medium-high heat, then cook the chicken for a few minutes on each side until it’s golden on both sides.
Remove the chicken from the pan, then add the butter. When it melts add the sliced mushrooms and cook for about 5 minutes until they turn nice and golden.
Chuck in the garlic and dried thyme and cook for a further minute before pouring in the chicken stock, double cream, and add the Dijon mustard.
Stir well, then get the chicken back into the pan. Cook until the sauce thickens and the chicken is cooked through.
Add the chopped parsley, stir it through, then taste for seasoning.
Dish it up and enjoy.