Preheat oven to 350°F and line a baking sheet with parchment paper or a silicon mat.
Whisk the flour, baking powder, salt, and cinnamon together in a medium bowl.
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar together on medium high until light and fluffy - about two minutes.
Add the eggs in one at a time, incorporating fully after each addition. Scrape down the sides of the bowl as needed.
Add in the vanilla.
Turn the mixer off and fold in the dry ingredients. Be careful to not over mix!
Lightly flour the lined baking sheet.
Divide the dough in half on the floured baking sheet and form each into a rectangular shape about 1/2” tall. If the dough is too sticky to work with, add a sprinkle of flour.
Bake the dough rectangles about 25 minutes. Remove them from the oven and let them cool about 5 minutes.
Turn the oven down to 275°F.
Transfer each rectangle to a cutting board and slice into 1” biscotti shaped pieces using a large, serrated knife.
Place the biscotti back onto the baking sheet. Bake each side about 15 minutes, 30 minutes total.
Let the biscotti cool on the baking sheet.
Whisk the glaze ingredients together.
Drizzle the glaze over the biscotti.