*Remove zest from orange in lengthwise strips with a vegetable peeler, and chop finely.
Preheat oven to 350 degrees.
Food Processor Method: In a medium bowl, sift together all but 1/4 c of the flour with the baking powder, baking soda, and salt, and whisk to mix it well.
In a food processor with the metal blade, process the sugar and orange zest until the zest is finely minced. Add the eggs and process for about 30 seconds or until thoroughly blended. Scrape the sides of the bowl.
With the motor running, add the oil and extracts and process until blended. Add the sliced almonds and process until finely chopped. Add the flour mixture and process for about 7 seconds or until the flour is almost incorporated. (There will be some flour clinging to the sides of the work bowl. Do not overprocess as the dough will be too stiff to incorporate the flour completely in the processor.)
Electric Mixer Method: Finely grate the orange zest. Finely chop the sliced almonds. Place them both in a medium bowl. Sift together all but 1/4 cup of the flour with the baking powder, baking soda, and salt and add to the nuts and zest. Whisk together to mix them well.
In a large mixing bowl, beat the sugar and eggs for several minutes, until very thick and pale in color. With the mixer at medium speed, beat in the oil and extracts. At low speed, gradually beat in the flour mixture.
For both methods: Scrape the dough (including any flour from the work bowl) onto a lightly flour counter and knead the dough, adding the remaining 1/4 c flour to form a soft, non-sticky dough.
Shape the dough into two 2-inch wide cylinders. Each will be about 7 1/2 inches long. Line up the whole almonds lengthwise in rows along the dough and press them well into the dough. With the palms of your hands, roll the cylinders on the counter, enclosing the almonds and maintaining the 2-inch diameters of the cylinders. Place the cylinders 2 inches apart on a cookie sheet. In a small bowl, stir together the sugar and cinnamon for the topping. Beat the egg white.
Brush the cylinders lightly with the beaten egg white and sprinkle them with the cinnamon topping.
Bake on the upper rack of the oven for 30 minutes or until lightly browned and very firm.
Cool the cylinders on the cookie sheet for 15 minutes or until just warm. Slip them off the sheet and onto a counter. With a serrated knife, cut diagonal 1/2 inch slices. Place the slices closely together on lightly buttered cookie sheets.
Toast the slices for about 8 minutes. Using a small metal spatula, turn them and bake for another 8 minutes or until golden brown. For even baking, rotate the cookie sheets from top to bottom and front to back halfway through the baking period. [I NEVER do this, because I think you lose too much of your heat when you open the door to do it, so you're no longer baking at the correct temperature. --Leti] Use a small, angled metal spatula or pancake turner to transfer the cookies to wire racks to cool completely.
Store in an airtight container at room temperature. Keeps several months.
Smart cookie hints:
* Unbleached flour has more gluten-forming proteins, which help to hold the almonds in the dough and make the dough less fragile.
* When the almonds are placed lengthwise, they do not fall out of the baked dough as readily and are more attractive when sliced.
* Biscotti can be tricky to cut into neat slices. If the cylinders are too hot or completely cold, the slices tend to break. When cutting the biscotti, hold the cylinder near the end being sliced and press it gently on top. If it is still crumbly, try popping it in the oven almonds is another solution, but they are less dramatic in appearance.