Line an 8x8 inch baking dish with parchment paper, leaving some overhang for easy removal.
In a medium saucepan over low heat, combine the Nutella and sweetened condensed milk, stirring until melted and smooth.
Add the semi-sweet chocolate chips to the mixture and continue to stir until fully melted and incorporated.
Remove from heat and stir in the vanilla extract and a pinch of salt to enhance the flavor.
If using, fold in the chopped hazelnuts to add crunch and texture.
Pour the fudge mixture into the prepared baking dish and spread it evenly using a spatula.
Refrigerate for at least 2 hours or until firm.
Once set, remove the fudge from the dish using the overhanging parchment paper and cut into squares.
Notes
Serve the fudge on a decorative plate, and dust with powdered sugar for an elegant touch. You can also drizzle melted chocolate over the top for added flair.