In a medium-sized saucepan, combine 3/4 cup chopped semi sweet or milk chocolate and 4 tbsp unsalted butter, cubed. Heat over medium heat and whisk until chocolate is melted completely.
Once chocolate has melted, whisk in 2/3 cup granulated sugar and 2/3 cup evaporated milk.
Bring to a boil over medium heat; once boiling, cook 8 minutes. Whisk constantly to avoid scorching or burning.
After 8 minutes, remove from heat and whisk in 1 tsp vanilla extract.
Allow to cool slightly before using or place in an airtight container. Store in refrigerator.
Notes
You can use chocolate chips for the chocolate pieces, but be sure to use a high quality brand. I like Guittard chips.
The hot fudge sauce will keep in the refrigerator for up to two weeks.
Reheat in the microwave in 30 second intervals, stirring after each interval until it is a pourable consistency.