Line an 8x8-inch baking pan with parchment paper. Leave extra paper hanging over the sides. This makes lifting and cutting the fudge much easier after it has chilled.

Place the sugar, evaporated milk, butter and salt into a medium saucepan. Cook over medium heat while stirring often. Bring the mixture to a gentle boil and cook for about five minutes.

Remove the saucepan from the heat. Immediately add the chocolate chips. Stir slowly until the chocolate melts completely and the mixture becomes smooth, shiny and creamy.

Add the miniature marshmallows and vanilla extract. Stir until the marshmallows melt into the warm chocolate mixture. If using chopped nuts, fold them in at this stage.

Pour the warm fudge mixture into the prepared pan. Spread it evenly with a spatula. Smooth the top gently so every piece will have a neat finish.

Leave the fudge at room temperature for about twenty minutes. Then place it in the refrigerator for at least two hours until it becomes firm and easy to slice.

Lift the chilled fudge from the pan using the parchment paper. Place it on a cutting board. Use a sharp knife to cut it into small squares or rectangles.

Arrange the fudge pieces on a serving plate or store them in an airtight container. Enjoy with coffee, tea or a glass of cold milk whenever you want a sweet treat.