Line an 8 x 8 inch pan with two pieces of parchment paper overlapping.
Add the chocolate and sweetened condensed milk to a large microwave safe bowl. Microwave in 30 second intervals, stirring between each until the chocolate is melted.
Stir in the Baileys, vanilla extract and salt if using.
Pour in to the prepared pan and spread until smooth on top. Place in the fridge for at least 4 hours or overnight.
Notes
Line the pan with parchment paper so you can easily get the fudge out when set.
When melting the chocolate and sweetened condensed milk in the microwave, use short intervals (30 seconds) and stir well between each. This prevents overheating and ensures a smooth, lump-free consistency.
Allow the fudge to set in the refrigerator for at least 4 hours. For optimal results, refrigerate overnight to let the flavors meld and the fudge to achieve the perfect consistency.
Before cutting, let the fudge sit at room temperature for a few minutes to make it easier to cut into neat squares. Use a sharp knife dipped in hot water for smoother cuts.