2 c (284 g) flour
1 1/2 c (298 g) sugar
1/4 tsp salt
1 1/2 tsp baking powder
1 2/3 c (198 g) hazelnuts, roughly chopped
1 Tbsp vanilla extract
4 or 5 eggs, room temp
Preheat the oven to 350F. Line two baking sheets with parchment and set aside.
Combine all of the dry ingredients in a mixing bowl. Add the vanilla. Begin adding the eggs one at a time, mixing well to incorporate after each addition. After adding the fourth egg, check to see if the dough is wet enough to clump together. If so, skip the fifth egg. If not, add it.
Divide the dough in half and form a log on each sheet. Shape it so that it is the same height and width throughout, about 2 inches smaller than the desired length of the final biscotti. Bake 20 minutes until puffed, spread and firm. Cool for five minutes on a rack, then slice into 1" pieces with a serrated knife. Place slices back on the pan with one cut side up, and bake 8-10 minutes until very dry. Flip cookies and bake another 8-10 minutes. Cool completely on a rack and store in an airtight container at room temp.