Place nuts on a small sheet pan and toast for 10 - 15 minutes. Set aside.
In a medium mixing bowl, cream butter & brown sugar for about 3 minutes.
Add the vanilla & eggs and thoroughly blend.
Add the flour and salt and mix just until combined.
I line a 9 x 13 baking dish with foil, one piece overhanging the length of the dish and another the width. Press into the corners of the dish. ( this makes it easier to cut nice even pieces, when taken out of baking dish. Spray with nonstick cooking spray.
I spray my fingers with non stick cooking spray ( I use crisco )...Pat our the dough evenly.
Place in oven and bake for 15 - 20 minutes or until edges are becoming a golden color.
About 5 minutes before finished baking, melt chocolate chips and I add 1/2 tsp veg oil to bowl and microwave in 30 second increments, until all is melted and smooth.
Take baking dish from oven, and place on cooling rack. Let cool for 5 minutes, then with an offset knife I spread the melted chocolate evenly.
Sprinkle evenly with hazelnuts, I press them down, lightly ~ just a little, so when cutting they don't so easily fall off.
Let cool completely, then grabbing the ends of foil, lift out of pan. Pull down sides of foil. Cut into several bars and serve.