Preheat the oven to 325ºF. Position a rack in the center of the oven. In a medium bowl, combine the flour, baking powder and cinnamon and mix thoroughly.
In a large bowl with an electric mixer, beat the brown sugar, butter, eggs, salt, and vanilla for 2 to 3 minutes, until thick and pale. Add the flour mixture a little bit at a time. Add in the hazelnut and dried cherries and mix on medium-low speed until all the ingredients are moistened.
Use a spatula to scrape out the dough onto a lined cookie sheet (I used a sheet for each log) and divide the dough in half (or do one log to make marge larger biscotti).
Spray hands with cooking spray; form each piece of dough into a 2 1/2-inch-wide log. Bake until dough is firm but gives slightly when pressed, about 20-25 minutes.
Let the logs cool for at least 15 minutes and then reduce oven temperature to 300 degrees.
Carefully place the loaves on a cutting board. Using a long serrated knife, cut each log on the diagonal into 1/2-inch-thick slices; place slices, cut side up, on sheet. Bake 7 minutes, flip biscotti, and bake 7 minutes more (it may only take 5 minutes on each side, every oven is different).
Set the sheet on a rack to cool completely. May be kept in an airtight container for up to 2 weeks