Crafting this delicious Oreo fudge can be easily achieved by following these simple steps:

1. Prepare the Baking Dish: Line an 8×8-inch square baking dish with parchment paper, allowing some overhang for easy removal later.
2. Melt Ingredients: In a medium saucepan, combine the semi-sweet chocolate chips, sweetened condensed milk, and unsalted butter. Cook over medium-low heat, stirring frequently until the chocolate is fully melted and smooth.
3. Add Vanilla: Once melted, remove the saucepan from heat and stir in the vanilla extract, ensuring it is well combined.
4. Incorporate Oreos: Carefully fold in the crushed Oreo cookies and mini marshmallows, ensuring they are evenly distributed throughout the chocolate mixture.
5. Transfer to Dish: Pour the fudge mixture into the prepared baking dish, spreading it evenly with a spatula or spoon to create a smooth top.
6. Add Toppings: If desired, crush additional Oreo cookies and sprinkle them on top of the fudge for an added touch of flavor and decoration.
7. Chill the Fudge: Place the baking dish in the refrigerator and allow the fudge to set for at least 2 hours until firm.
8. Cut into Squares: Once set, lift the fudge out of the dish using the parchment overhang and cut it into small squares or rectangles.
9. Store: Store the Oreo fudge in an airtight container at room temperature or in the refrigerator for up to two weeks.

These easy steps provide a clear path to creating the perfect Oreo fudge, ensuring deliciousness from start to finish.