Combine the milk and white chocolate chips in a saucepan. Heat the mixture over low heat, stirring constantly, until the chocolate is completely melted. Remove the pan from the heat.
Stir in the vanilla. Add marshmallows and pistachios, stir to mix. Cut back on stirring If you like little pieces of marshmallow.
Pour the fudge into the prepared pan and smooth the top slightly. Refrigerate to set, 1½ hours or longer.
Recipe by Cindy's Recipes and Writings at https://www.cindysrecipesandwritings.com/holiday-fudge-round-up/