Line an 8×8 or 9×9 square pan with parchment paper and coat with cooking spray.
In a microwave safe bowl, combine the sweetened condensed milk, chocolate chips and butter. Microwave on high for 5 minutes.
Remove and whisk vigorously, adding the vanilla. If there are still small chunks, return to microwave for 30 seconds.
Transfer mixture to the prepared pan and sprinkle with mini chocolate chips, if desired. Press lightly into the tacky surface to stick.
Place in the refrigerator to set for an hour. Cut into 16 small squares.
If you've tried this recipe, come back and let us know how it was in the comments or star ratings.
Notes
Storage: This 4 ingredient chocolate fudge can be stored at room temperature for 2 to 3 weeks. Wrap it in wax paper or store it in an airtight container with a lid or aluminum foil.Freezer: Store fudge in the freezer for up to 3 months. Avoid refrigerating, though, as it can rob fudge of its moisture.