For 6-8 servings:
Set a rack in the middle level of the oven and preheat to 350 degrees. In a bowl combine the flour, sugar, baking powder, and cinnamon; stir well to mix. Stir in the almonds. In another bowl, whisk the eggs with the vanilla then use a rubber spatula to stir into the dry ingredients. Continue to stir until a stiff dough forms. Scrape the dough out onto a lightly floured work surface and divide it in half. Roll each half under the palms of your hands into a cylinder a little shorter than your baking sheet. Place the logs of dough on the baking sheet, making sure they are neither too close to each other nor to the sides of the pan. Press down gently with the palm of your hand to flatten the logs. Bake for about 25 to 30 minutes, or until the logs are well risen and have also spread to about double their original size. The logs are done when pressed with fingertip they feel firm. Place the pan on a rack and let the logs cool completely. Reset the oven racks in the upper and lower thirds but leave the temperature at 350 degrees. Place one of the cooled logs on a cutting board and cut it diagonally into slices 1/3-inch thick. Arrange the biscotti on the prepared pans, cut side down. It isn't necessary to leave space between them. Bake the biscotti for about 15 or 20 minutes or until they are well toasted. Cool the pan on a rack. Store the cooled biscotti between sheets of parchment or wax paper in a tin or plastic container with a tight-fitting cover.