Clean the duck legs of excess skin and fat and season with salt and pepper. Wrap them in baking paper, then in aluminum foil and cook in the oven for 2 hours at 180°C (356°F). Just make sure to add a little water in your pan/tray.
Cut the cabbage into two pieces, spread with soft butter and season with salt and pepper.
Remove the duck thighs from the foil and place them in a baking tray with the Chinese cabbage. Roast for about 10 minutes in a well heated oven until the skin on the duck turns golden brown and crispy, and the cabbage begins to soften and the leaves begin to blacken at the edges.
To serve, add a little cranberry jam, which goes perfectly with roasted Napa cabbage and tender duck.