Line an 8x8 baking dish with parchment and lightly spray with nonstick cooking spray.

Combine sugar and evaporated milk in a heavy-bottomed saucepan. Cook over medium heat, stirring constantly until mixture boils, about 5 mins.

Turn heat to low and continue cooking while stirring constantly, until the liquid has reduced by half, about 10 minutes.

Remove from heat and immediately add chocolate, corn syrup, butter, and vanilla.

Vigorously stir until chocolate has melted and fudge is smooth and creamy. If using, stir in nuts or dried fruit.

Immediately pour into the baking dish and quickly smooth the top with an offset spatula. The top will set quickly.

Chill until firm, about 2 hours.

Cut into squares, share with friends, and keep leftovers in a cute parchment lined tin in a cool dark place.