Line an 8×8-inch pan with parchment paper
Combine 2 cups sugar, 1/2 cup unsalted butter, 2/3 cup evaporated milk, and a pinch of salt in a saucepan
Heat over medium heat, stirring until the butter melts and the sugar dissolves
Bring the mixture to a full boil
Boil for 4 to 5 minutes, stirring constantly
Remove from heat
Stir in 2 cups chocolate chips and 1 teaspoon vanilla extract
Mix until smooth and fully melted
Add 1 cup chopped nuts if desired
Pour the mixture into the prepared pan
Smooth the top with a spatula
Let it cool at room temperature
Refrigerate until firm
Lift out the fudge and cut into squares