In a small bowl, empty contents of crust mix. Toss together crust mix and 3 tablespoons melted butter. Divide crust evenly between cups. With the back of a teaspoon, gently press down crumbs to form a crust. Set aside.
In a large bowl, empty contents of filling mix into bowl. Add cold milk and beat on medium speed until mixture becomes thick. Spoon filling mix into paper liners. Using the back of a spoon, evenly spread filling out over crust.
Knead fudge topping packet for several seconds. Snip off one corner and squeeze a small amount of topping onto each dessert bite. With the back of a spoon, gently spread out, optional.
Place muffin tin in the freezer for one hour or longer before serving. Store in the freezer.