For 6 people
Line a pan with aluminum foil. Over medium heat, add the condensed milk to a small saucepan and whisk in the cocoa powder. Stir in the chocolate chips and stir until combined. Stir in the vanilla extract. Pour your mixture into the pan. Top with the marshmallows. Refrigerate the mix for five hours. Remove the fudge by lifting the aluminum foil then cut to serve.