Step 1: Prepare Your Baking Dish - Line an 8x8 inch baking dish with parchment paper, allowing some overhang for easy removal later.
Step 2: Melt the Chocolate and Butter - In a large saucepan over medium heat, combine the broken pieces of Hershey's milk chocolate, semi-sweet chocolate chips, and salted butter. Stir continuously until everything is melted and smooth.
Step 3: Add the Sugar and Evaporated Milk - Once the chocolate mixture is smooth, add the sugar and evaporated milk. Stir well to combine and continue cooking for about 5 minutes until the mixture thickens slightly.
Step 4: Incorporate the Marshmallows and Vanilla - Remove the saucepan from heat and fold in the mini marshmallows, frozen mini marshmallows, and vanilla extract.
Step 5: Add Nuts - Fold in the chopped walnuts or pecans for added crunch.
Step 6: Pour into the Baking Dish - Carefully pour the fudge mixture into the prepared baking dish and smooth the top.
Step 7: Chill and Set - Place the baking dish in the refrigerator and let the fudge chill for at least 4 hours, or overnight if possible.
Step 8: Cut and Serve - Once set, lift the fudge out using the parchment paper and cut into squares.
