Step 1:

Prep & Boil: Add the sugar, evaporated  milk, and  butter to a saucepan over medium heat. Bring to a boil, stirring often. Once boiling, continue to boil for exactly 5 minutes.

Step 2:

Add  Chocolate & Marshmallows: Remove the saucepan from the heat. Whisk in the chocolate chips and marshmallows. Continue to stir until the marshmallows are completely melted and the mixture is smooth.

Step 3:

Mix In & Set: Mix in the vanilla extract and pecans. Pour the fudge mixture into the bottom of a well-greased 9×9-inch baking dish.

Step 4:

Chill & Serve: Place the dish into the fridge or freezer to set until the fudge is hardened. Once firm, cut into 36 pieces and serve.