Preheat the oven to 180°C.
Heat the oil in a casserole dish and brown the lightly salted chicken pieces all over.
Meanwhile, thinly slice the leek and coarsely chop mushrooms.
Transfer the chicken to a plate. In the same dish, soften the mushroom and leek pieces for a couple of minutes, then add the paprika and rosemary leaves. Stir for a few seconds the then pour in the wine and deglaze the pan.
Put the chicken pieces back, season with salt& pepper, then bake (skin facing up) for 45 minutes, or until golden brown.
Remove the chicken to a plate, cover with foil and rest.
Pour the broth over the mushroom-onion jus and reduce it to a thick, textured sauce on the hob.
Serve the chicken with the mushroom sauce.