Peel the asparagus. Place them one by one on the baking sheet. Pour white wine. Dust with powdered sugar. Spread the salts and flakes of butter on top. Seal with 2 sheets of aluminum foil. Make sure that the sheets of aluminum foil overlap as much as possible. Place in the oven for 45 minutes (depends on the thickness of the asparagus) at 180 degrees. The asparagus are allowed to turn brown.