Step 1: Prepare the pan

• Line an 8×8-inch square baking pan with parchment paper, leaving some overhang for easy removal. Lightly grease the parchment with butter or cooking spray.

Step 2: Melt the chocolate mixture

• In a medium saucepan over low heat, combine the chocolate chips, sweetened condensed milk, and butter. Stir continuously until the mixture is smooth and melted.

Step 3: Add flavorings

• Remove the saucepan from heat and stir in the vanilla extract and a pinch of salt. Mix until fully incorporated.

Step 4: Add optional mix-ins

• If using nuts, dried fruit, or marshmallows, fold them into the fudge mixture at this stage.

Step 5: Pour and spread

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

Step 6: Chill the fudge

• Refrigerate the fudge for at least 2–3 hours, or until it is firm and set.

Step 7: Slice and serve

• Use the parchment overhang to lift the fudge out of the pan. Cut into squares and serve.