Line a 9x13-inch baking dish with parchment paper.

Combine sugar, butter, and evaporated milk in a 2-quart saucepan; cook, stirring constantly, until a candy thermometer reads 245 degrees F (118 degrees C), about 10 minutes. Add caramel to milk mixture; cook until temperature returns to 245 degrees F (118 degrees C), about 10 minutes.

Remove saucepan from heat and stir marshmallow creme and vanilla extract into caramel mixture. Pour mixture into the prepared baking dish, evenly spreading into the dish. Sprinkle salt over the fudge. Lightly swirl fudge using a butter knife to slightly submerge the salt into the fudge. Cool fudge completely before cutting into squares.