Melt the butter and oil in a strong frying pan and fry the chicken for five minutes on each side until golden.
Remove to a warm plate,and add the bacon and onion to the pan. Cook for five minutes or until the onion is soft. Add the mushrooms and thyme,tossing well,then add the wine and bay leaves. Boil for two minutes,then return the chicken to the pan and add the stock.
Simmer,covered,for 30 minutes,or until the chicken is tender and cooked through. If you find it too soupy,simmer uncovered for another 10 minutes.
Just before serving,remove the chicken to a warm plate,and whisk the cream and mustard,salt and pepper into the mushrooms over gentle heat.
Return the chicken to the pan,scatter with baby spinach and heat through. Dust with paprika and serve.