Line a 9x9 baking dish with foil or parchment paper, leaving an overhang so that you'll easily be able to lift the fudge out of the pan.
Unwrap the candy bars and place them in a single layer in the baking dish.
Add the condensed milk and chocolate chips to a microwave safe bowl and microwave for 1 minute. Stir and then continue microwaving and stirring in 30 second intervals until the chocolate is fully melted.
Stir the vanilla in the fudge mixture until combined.
Pour the chocolate fudge over the candy bars and smooth the top. Sprinkle the mini Reese's over the top. Press the candy bars into the fudge.
Place in the refrigerator to set for at least 1 hour before cutting into small pieces.
Feel free to mix this up with any candy bar you prefer!