1Preheat oven to 350 degrees F (175 degrees C). Toast the almonds until golden brown.
2Let almonds cool, then chop into 1/4 inch pieces.
3Set oven temperature to 325 degrees F (165 degrees C).
4Cream the butter and sugar until smooth and creamy. Beat in the eggs until smooth. Zest the orange, add to mixture and stir well. Add the orange-flavored liqueur and cinnamon. Mix in the flour, baking powder and salt. Beat until just mixed. Stir in the chopped almonds. Divide the dough in half on a lightly floured board and form into long rolls, about 2 inches in diameter and 10 inches long.
5Set the rolls on a cookie sheet and bake for about 25 minutes, or until they are brown on top.
6Let the rolls cool for 5 minutes, then slice diagonally 1/2 inch thick.
7Lay slices back flat on cookie sheet and cook for another 10 minutes. Flip biscotti over and cook for another 10 minutes. Let cool on wire racks. If you keep these in an airtight container, they will keep for months.
Footnotes
Tip
Aluminum foil can be used to keep food moist, cook it evenly, and make clean-up easier.