In a medium-sized, microwave-safe bowl, combine the sweetened condensed milk and chocolate chips. Microwave on high for 30 seconds, then stir vigorously. Repeat this process in 30-second intervals until the chocolate is nearly melted and glossy, about 1 to 2 minutes.

Once the chocolate is almost melted, stir the mixture until it becomes completely smooth and luscious. If necessary, microwave for an additional 10-15 seconds.

Pour in the Baileys Irish Cream liqueur, gently folding it into the mixture. Stir until fully combined.

Introduce 1 teaspoon of vanilla extract and a pinch of salt to the mixture. Stir well to distribute evenly.

Line an 8x8 inch square baking pan with parchment paper, ensuring it overhangs the edges for easy removal.

Pour the fudge mixture into the prepared baking pan, spreading it evenly with a spatula.

If desired, sprinkle your choice of toppings over the fudge and gently press them into the surface.

Cover the pan with plastic wrap and chill in the refrigerator for at least 2 to 3 hours, or overnight.

Once chilled, lift the fudge out of the pan using the parchment paper and cut into squares.

Arrange your fudge squares on a plate for serving and store leftovers in an airtight container in the refrigerator.