Preheat oven to 325 degrees.
Spread hazelnuts on the cookie sheet and bake for 7 minutes.
Remove hazelnuts from oven and wrap in a tea towel.
Fold tea towel closed and roll the nuts on counter to remove as much as the skin aspossible.
Discard the skin and coarsely chop the nuts.
Line the cookie sheet with parchment paper.
In a large bowl, beat the eggs plus egg yolk with a hand mixer.
Add the sugar and beat until the mixture is pale and thick.
In a small bowl mix the gluten free flour blend and cinnamon.
Add gluten-free flour and mix on low speed until well blended.
Add the orange zest and vanilla and mix on low just until combined.
Form dough into a long flat log.
Bake in oven for 25 minutes.
Remove from oven and cool for about 10 minutes.
Slice dough into 1 inch slices and carefully lay slices cut-side up on cookie sheet. Cookies are very delicate at this point.
Bake for another 10-15 minutes.
Remove from oven and cool.
This recipe made 10-12 large biscotti cookies.
You can easily make 2 smaller logs instead of one large one and have smaller biscotti cookies.