Heat 1 tablespoon of the olive oil in a large ovenproof frying pan or casserole dish over a medium heat. Add the onion, celery, carrots, herbs and bay leaf then season to taste and give a good stir. Cook, stirring occasionally for 10 to 15 minutes until soft, without browning the vegetables. Remove from the pan and set aside.
Meanwhile, peel the potatoes and slice into 0.5cm slices, or thinner if possible. Leave them in a bowl of cold water to prevent browning.
In a bowl, mix together the flour, paprika, some salt and black pepper and dredge the chicken pieces in the flour mixture. Heat another tablespoon of oil in the same pan as the vegetables and brown the chicken on a good heat for a few minutes until they are browned on all sides. Remove the chicken from the pan.
Pour the white wine into the pan to deglaze any yummy brown bits, then turn off the heat and place a layer of the peeled sliced potatoes in the bottom. Put the chicken on top, and then put in the vegetables, so that they lie in-between the chicken pieces. You should have a tablespoon of the flour mix left over, sprinkle this over the chicken and vegetables and season. Pour in the stock and drizzle over the remainder of the olive oil.
Lay the rest of the potatoes on top, in overlapping layers and brush with the melted butter.
Bake covered in the preheated oven for 30 minutes. Remove the dish from the oven and take off the lid to let the potatoes brown as they cook through.
Return to the oven and cook for around another 45 minutes, until the potatoes are golden brown and a knife goes through the potatoes easily. Remove from the oven and serve.
If you want a slightly healthier version of this dish, don't brown the chicken in oil first, just put it in the pan with the sauteed vegetables and sprinkle the flour on top.