For the duck thighs, Remove the skin
Brown the ducks thighs in a large pan with a little bit of oil. Season with salt and pepper. Cover and cook for 30 minutes. Check regularly.
After 30 minutes, pour in the red wine and chopped shallot. Cook for another 40 minutes, until the wine has been almost completely absorbed. Keep the juice/sauce for later.
Let cool and remove the meat from the bones. Cut into small pieces.
Cut the acorn into dices. Peel the sweet potatoes. In a saucepan, boil a large amount of salted water. Cook the sweet potatoes and the acorn squash for 20-25 minutes until tender. Drain and puree the potatoes and acorn squash. Add a little bit of butter and heat in a saucepan to prevent the puree from drying out. Season to taste
Preheat the oven on 350F
Put some pure at the bottom of a shallow gratin dish, Top some meat (and meat juice if you have some). Cover with the rest of the puree and top with grated cheese.
Bake for 15 minutes and put your oven on grill for the last 2 minutes.