Step 1

Line an 8x8-inch square baking pan with aluminum foil extending up the sides. Spray lightly with nonstick cooking spray.

Step 2

Combine the chocolate chips, condensed milk, and butter in a large microwave-safe bowl. Microwave the bowl for 30 seconds at 50% power.

Step 3

After 30 seconds, stir well. At this point, the butter and chips will have started to melt, but you will still have plenty of unmelted chocolate in the bowl.

Step 4

Continue to microwave the fudge in 30-second increments at half power. Stir well after every 30 seconds. Depending on your microwave, it will most likely take 2-3 minutes of total heating time to melt everything.

Step 5

Once the chocolate is melted, add the vanilla extract and salt, and stir well.

Step 6

If your fudge still looks "rough" or broken, continue to heat it at half power in short bursts, stirring very well between each heating session. Stop when the fudge is glossy and smooth.

Step 7

Immediately scrape the fudge into the prepared pan and smooth it into an even layer.

Step 8

Refrigerate the fudge until set, for about 2 hours. Once set, cut into 1-inch squares and serve at room temperature.

Step 9

Extras can be stored in an airtight container at room temperature for two weeks, or in the refrigerator for up to 3 weeks. It will gradually dry out, so be sure to wrap it well if you are planning on storing it for an extended period of time.