Follow these step-by-step instructions carefully for a flawless batch of Easy Marshmallow Fudge. The key is to have all your ingredients measured and ready to go before you begin, as the final steps happen very quickly.

1. Preparation is Key: Prepare a 9×13 inch baking pan by lining it with parchment paper or aluminum foil, leaving an overhang on the two long sides. This “sling” will make it incredibly easy to lift the entire block of fudge out for cutting once it has set. Lightly grease the foil or parchment paper to ensure no sticking.
2. Measure and Combine: In a large, heavy-bottomed saucepan, combine the granulated sugar, cubed unsalted butter, and evaporated milk. A heavy-bottomed pan is crucial as it distributes heat evenly and prevents the sugar mixture from scorching on the bottom.
3. The Crucial Boil: Place the saucepan over medium heat. Stir constantly with a wooden spoon or heat-resistant spatula until the sugar has dissolved and the butter has melted completely. Bring the mixture to a full, rolling boil. This is a boil that you cannot stir down. Once it reaches this stage, set a timer and continue to boil for exactly 5 minutes, stirring constantly to prevent it from burning or boiling over. This step is vital for cooking the sugar to the “soft-ball stage” without needing a candy thermometer, ensuring the fudge will set correctly.
4. Prepare for the Final Mix: While the sugar mixture is boiling, have your semi-sweet chocolate chips, marshmallow creme, vanilla extract, and pinch of salt ready in a large heatproof bowl.
5. Combine and Melt: After the 5-minute boil is complete, immediately remove the saucepan from the heat. The mixture will be extremely hot. Carefully pour the hot sugar syrup over the chocolate chips and marshmallow creme in the large bowl.
6. Mix Until Smooth: Add the vanilla extract and salt. Begin to stir the mixture vigorously with a wooden spoon or spatula. At first, it may look separated or lumpy, but keep stirring. The residual heat from the sugar syrup will melt the chocolate chips and marshmallow creme. Continue stirring until the mixture is completely smooth, glossy, and uniform in color. This process should take about 2-3 minutes. You must work quickly here, as the fudge will begin to set as it cools.
7. Pour and Spread: Once the fudge is smooth and glossy, immediately pour it into your prepared 9×13 inch pan. Use your spatula to quickly spread it into an even layer, pushing it into the corners.
8. Chill and Set: Let the fudge cool at room temperature for about 30 minutes before transferring it to the refrigerator. Allow the fudge to chill in the refrigerator for at least 4 hours, or preferably overnight, until it is completely firm and set.
9. Cut and Serve: Once the fudge is firm, use the parchment or foil overhangs to lift the entire block out of the pan and onto a cutting board. Use a large, sharp knife to cut the fudge into small, 1-inch squares. For extra clean cuts, you can dip the knife in hot water and wipe it dry between slices.