Marinate the duck 12 hours with 1 cup of maple syrup while turning over a few times.
Preheat the oven at 350˚F.
In a roaster pan, poor 1 cup of water and lay the duck (breast up) on a small grill.
Cook covered 2 hours while basting with the cooking juice every 15 minutes.
Uncover and cook 30 minutes en while basting.
Sprinkle the duck with maple flakes and roast the skin, about 5 minutes.
Sauce:
In the duck fat, quickly brown the green onions deglaze with the apple vinegar the Rubicon.
Add the apples and the duck stock. Simmer 10 minutes or until apples are tender. Let cool and strain the sauce in a blender to obtain a smooth texture. Add the 3 tbsp of maple syrup and mix.