1- Slice the onions then, brown them in a large pan with butter and oil. When they have taken on a nice color add the brown sugar and continue the cooking for another 2 minutes then remove from heat.
2- Peel the potatoes especially, do not wash them, just wipe them and slice them.
3- Preheat your oven to 160°(th 5-6).
4- In a deep ovenproof dish (a Dutch oven for example) put a layer of potatoes, season then put a layer of onions and finally one last layer of potatoes
5- Dilute the chicory with the poultry stock and pour over your potatoes.
Cook for 1 hour 30 minutes, checking regularly. If the top browns too much, cover with aluminum foil.
6- Enjoy your potatoes Boulangère style as they eat them at Grandma Sophie's place in Tourcoing with for example a sausage "cut with a knife" roasted and a good farmhouse beer
(to pair with the sweet taste of the caramelized onions)
of course you can, if you are from another region, remove the chicory and replace the liquid with beef juice (pot-au-feu) lamb or poultry (poule au pot)
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