Cut the mushrooms into large slices.
Cut the onion into small cubes.
Melt the butter in a frying pan. Salt and pepper the chicken drumsticks and place them in the frying pan.
Fry the chicken drumsticks over medium heat for 5-7 minutes until golden brown.
Add mushrooms and onions to the chicken. Fry everything together for another 5 minutes.
Add cream and a teaspoon of mustard to the pan. Stir gently.
Transfer the contents of the pan to a baking dish. Add a few sprigs of thyme. Place the chicken in the oven for 10 minutes until done.