Preheat oven to 350F, get the middle rack set on the oven,  grease an 8x8 baking pan or line with parchment paper on the bottom.  If using fresh hazelnut, break open, separate the nuts. Toast them dry in a pan, over stove top for 15 to 20 minutes on low medium flame. Place them over a paper towel and rub to remove the skin. Chop them coarsely and keep aside.

Sift together all-purpose, salt and cocoa powder and keep aside. Combine melted butter, white sugar, brown sugar and vanilla extract. Beat until light and fluffy (low speed using electric hand mixer), adding eggs one at a time. Gradually add the flour and cocoa mixture and mix gently until it forms a thick gooey paste (do not beat at this stage). Fold in the semi sweet chocolate chips, milk chocolate morsels and chopped nuts. Spread the batter evenly in the prepared dish and bake for 35 minutes or until an inserted toothpick in the center of the dish, comes out clean.  Place pan on wire rack, cool for 10 minutes and run a very thin sharp knife around outside edge of brownie to loosen from side of pan, gently remove the brownie slab along with the parachment paper and cool again for 20 minutes.  Don't try to cut brownies when warm, it may go shapeless. When cooled completely cut them into small squares and store in a-tight box for 2 weeks.