Fill a saucepan with 1/3 of water and bring it to a simmer. Reduce the heat to low.
Place a large bowl on top of the saucepan, making sure that the bowl doesn't touch the water.
Add chocolate chips, condensed milk, butter, and vanilla extract to the bowl.
Mix the ingredients regularly.
The fudge mixture is ready once all the ingredients have melted and achieved a smooth, consistent texture.
Add hazelnuts.
Fold hazelnuts in with a silicone spatula.
Line a cheesecake pan with parchment paper.
Transfer the fudge mixture into the pan.
Smooth the fudge with a clean silicone spatula.
Make sure the fudge is smooth on the top and reaches all corners.
Sprinkle hazelnuts evenly on top.
Gently press hazelnuts with a clean silicone spatula.
Refrigerate for 2 hours, but better overnight.
Cutting fudge
Once the fudge has hardened, prepare a cutting board, disposable gloves, and a large knife for cutting the fudge. Have a wet kitchen towel on hand to wipe the knife after each cut.
Remove the fudge from the fridge
Peel it off the parchment paper.
Place it on the cutting board.
Score the fudge using a 5-wheel pastry cutter.
Turn the fudge block 90 degrees and score again to create even squares.
Cut the fudge block along the scored lines, wiping the knife with a wet kitchen towel after each cut.
Turn the fudge block 90 degrees and push the pieces back together. Finish cutting the fudge using the scored guidelines.