Preheat the oven to 180 °C (350 °F).
Season the duck legs with salt and pepper.
In a large skillet, melt the duck fat over medium heat.
Fry the duck legs for 3 to 4 minutes on each side. Transfer the duck legs to a baking dish. Remove most of the excess fat from the pan, leaving 30 ml (2 tbsp) in the pan.
In the same pan, sauté the shallots for 1 minute, stirring.
Add the ale, duck stock, maple syrup and thyme. Stir.
Pour the beer mixture into the baking dish. Arrange the parsnips, carrots and baby potatoes around the duck legs.
Cover the baking dish with a sheet of aluminum foil. Bake in the oven for 1.5 to 2 hours, until the meat easily comes off the bone.
Remove the aluminum foil from the dish. Set the oven to Broil and broil and for 2 to 3 minutes, until the skin of the duck legs is golden and crispy.
Remove the duck legs and vegetables from the baking dish. Transfer the broth to a saucepan. Return the duck legs and vegetables to the dish. Cover with aluminum foil and keep warm in the oven at 100 °C (200 °F).
Bring the broth to a boil, then simmer over medium-high heat for 15 to 20 minutes, until the broth has reduced by half.
Serve the duck legs and vegetables with the broth.