This chicken dish is tasty, fairly quick and easy enough for a 'new' cook to impress dinner guests. A look into the fridge and store cupboard was the source of invention for this - plus limited time and the desire for a fairly healthy meal.
Slit the chicken breasts partly through the side, to create an 'envelope'. Try to slice at the thickest point and not all the way through. Spread 1 tablespoon of cream cheese inside the chicken breast and press the two sides together to reform the shape of the breast. Sprinkle with ground pepper to taste. Put to one side.
Melt the butter in a frying pan and gently fry the onions and mushrooms until the onions are soft. Turn up the heat to a medium/high level and add the chicken. Cook on one side for about 5 minutes (depending on size) or until cooked on that side. Turn each breast over and cook for a further 5 minutes (again depending on size) or until cooked. Try not to over cook - but always ensure the chicken is completely cooked. Don't worry if the cream cheese starts to leak out of the breasts - it all adds to the flavours later.
Turn the temperature back down a little, and add the wine (or water) to the pan (around the chicken). Followed by the mustard, thyme and stock cube. Bring to the boil. Let this gently simmer for 10 minutes. Serve with whatever is preferred - but it is good to have something to absorb the sauce. Leftovers freeze very well.
I've usually add some garlic when cooking the onions and mushrooms, but that is just personal preference.