Line an 8-inch square baking dish with parchment paper.
In a 3-quart saucepan over low heat, melt the chocolate chips with the sweetened condensed milk and salt.
Once completely melted and creamy, remove the chocolate mixture from the heat, and stir in the vanilla extract and chopped nuts (optional, of course).
Pour the mixture into the baking dish, and use your silicone spatula to spread smooth and level.
Place the fudge into the refrigerator for a minimum of 2 hours to firm.
Once firm, remove the fudge by lifting the parchment paper, then slice into 64 bite-sized pieces (or 48 indulgent pieces, if you prefer).
Store the fudge in the refrigerator or freezer, in an airtight container between layers of parchment paper. If kept in the freezer, this fudge requires no defrosting because it will not freeze solid. It will just be a touch more firm, but still ready-to-eat immediately upon removal.