To a large bowl, or bowl of stand mixer, add in the sugar and the softened butter. Mix thoroughly until no butter lumps or streaks remain. Beat in the olive oil until smooth and evenly incorporated. Add anise seeds, extract and ground anise and liqueur of choice.
Beat in the eggs until the mixture is pale, 2-3 minutes using a stand mixer or 4-5 if whisking by hand.
Add the almonds or nuts of choice, and mix. If using a stand mixer, be sure to scrape down the bowl to ensure even ingredient incorporation.
Add the flour and the baking powder, and mix until a smooth batter is formed. If using a stand mixer, I like to finish mixing by hand to ensure all ingredients, inlcuding those that may lurk on bottom of bowl, are incoroporated.
Cover the bowl and refrigerate for up to 2 days, and a minimum of 4 hours. This allows dough to firm for easy log shaping.
After cooling, prepare to bake. Preheat oven to 375F. Line 2 standard sheet pans with parchment. Arrange 1 rack in middle of oven and 1 rack in lower third of oven.
Working with the cold dough, divide it into 4 portions. Lightly grease your hands and work surface (you could also use flour), and roll 1 portion (so 1/4) of the dough into a log that is about 8-10" long, and about 1 1/2" thick. My tip here is that the rounder the log, the taller/thicker the biscotti, to aim for a cylinder shape as much as you can.
Transfer the logs to the baking sheets, re-shaping as needed. Do not worry if the logs are not perfect, they will bake/puff up and out.
Bake logs for 15-20 minutes, rotating the pans half-way through. Bake until logs are puffed and firm.
Remove from oven and allow to cool for about 10 minutes. Using a sharp, non-serrated knife, cut into 1/2" slices. Place back on sheet pans.
Bake for 5-7 minutes, or until just golden. Flip the cookies, and bake again for 5-7 minutes, rotating the pans from middle to bottom, until golden. Allow to cool on cooling racks until completely cool.
Store in containers or bags, at room temp or in the freezer.