Put the potatoes into a large pot, cover with water and bring to a boil over medium heat. Salt the water and cook the potatoes until tender. Drain and return the potatoes to the hot pot. Add the Camembert and milk and toss to coat the potatoes in the cheese (the mixture will look slightly mashed). Stir in the lemon zest and season with salt and pepper, to taste. Transfer to a serving bowl, garnish with lots of chives and serve.