Season the chicken legs with salt and pepper. Heat the clarified butter in a large saucepan over medium-high heat. Fry the bacon for 5-7 minutes until crispy, then remove and set aside. Fry the chicken legs in the same saucepan until well browned on all sides, about 5-7 minutes. Remove and set aside. Quarter the mushrooms and fry them for 3-4 minutes until lightly browned, then remove and set aside.
In the same saucepan over medium-high heat, fry the whole peeled potatoes and shallots for 5-7 minutes, stirring occasionally, until they begin to brown. Add the whole garlic cloves and fry for 1 minute. Pour the chicken broth into the pan, scraping up any browned bits from the bottom. Layer the fried chicken legs on top of the potatoes and shallots, then the mushrooms, then spread the crispy bacon over the top.
Cover the saucepan with a lid and cook in a preheated oven at 180°C (356°F) for 50 minutes. In a small bowl, mix the cornstarch with cold water to make a smooth paste. Remove the saucepan from the oven, stir the cornstarch mixture into the sauce to thicken it, and serve immediately.