Preheat the oven to 190'C.
Peel the potatoes and then thinly slice on a mandolin.
Peel and finely dice the onions. Pick the leaves from the thyme and rosemary. Chop the herbs finely.
Heat a large frying pan and then add a knob of butter. Add the onions to the pan along with 3 or 4 sprigs of thyme. Sauté for 3 minutes, stirring every once in a while. Add the balsamic vinegar to the pan and continue cooking until all the liquid has evaporated. Mix the onions with the sliced potatoes.
Line the base of a large ovenproof dish with the potatoes and onions. Season with salt and pepper and then sprinkle over a few thyme leaves.
Bring the stock to the boil and then ladle it over the potatoes. Chop the remaining butter into small pieces and sprinkle over the top. Transfer to the oven and bake uncovered for approximately one hour - check if the potatoes are cooked through using the tip of a sharp knife.
«Maris Piper, King Edward or Desirée potatoes work best for the pommes boulangères.»
A traditional French recipe for layers of potatoes cooked with thyme, rosemary and chicken stock. A great alternative to roast potatoes.