Rinse the skate wings thoroughly under cold water to remove any viscous skin residue.
Prepare the mushroom duxelles: Finely chop one shallot and sweat it in a little butter until translucent. Add the button mushrooms, diced into fine brunoise, and cook gently until they release their moisture and soften. Stir in the remaining two finely chopped shallots.
Arrange the skate wings in a baking dish. Spoon the duxelles over the top, then pour in the white wine and fish stock. Dot with the remaining butter cut into small pieces, and season with salt and freshly ground pepper.
Cover the dish with parchment paper and warm gently on the stovetop. Transfer to a preheated oven at 180°C, basting frequently with the cooking juices.
After 10 minutes, remove the parchment paper and increase the heat to 200°C. Continue basting until the liquid has reduced almost completely.
Finish by sprinkling with chopped parsley and serve straight from the baking dish.
Recommended garnish: Cabbage with lardons and mushroom caps.
