Step 1

Line an 8-inch greased square pan with parchment paper, leaving some overhang to make it easier to remove from the pan.

Step 2

In a saucepan, melt butter over medium-low heat.

Step 3

Add the chocolate and stir using a rubber spatula until the chocolate begins to melt (You can increase the heat a little but be careful, chocolate scorches quickly)

Step 4

Once the chocolate begins to melt, stir in the sweetened condensed milk.

Step 5

Once the milk is worked in completely, turn off the heat and add salt and vanilla extract if using.

Step 6

Quickly pour the batter into the prepared pan and spread it into an even layer using an offset spatula. (See note)

Step 7

Cover and refrigerate overnight to set.

Step 8

Once set, remove from pan and cut into even-sized 2-inch squares. (Tip: wiping off the knife after each cut creates clean slices)

Step 9

Store fudge in an airtight container between layers of parchment paper in the fridge or counter.