A thin, dry “skin” forms on the surface of puddings because as the mixture is heated, two things happen: Water evaporates, and proteins and sugar become more concentrated. Together, this results in a dry barrier on the liquid's surface.

How do I stop my skin from forming in pudding?

Cover each with a piece of plastic wrap, gently pressing the plastic directly onto the surface of the pudding to prevent a skin from forming as it cools. Refrigerate until well chilled, at least two hours.

How do I stop my chocolate pie skin from forming?

Take off the heat and immediately add the chopped chocolate, whisk vigorously to combine. Add the cold butter and vanilla bean paste or extract. Pour on top of the crust in the pie dish and place a piece of plastic wrap/ cling film directly on top, this helps prevent a thick skin from forming.