Preheat your oven to 350°
In a mixing bowl, add your dry ingredients except the sugar. Whisk to combine. In a stand mixture fitted with a paddle attachment, beat your butter and sugar on medium until fluffy and well combined. About 2-3 minutes. Add in 1 egg at a time and continue to mix. Be sure to scrape the sides of the bowl after each addition of ingredients. Next add in your extracts and tahini. Continue to mix on medium and gradually add in the flour mixture Don't over mix.
Next, fold in your chocolate and pistachios with a spatula. Dump the mixture onto a sheet pan lined with parchment paper. Shape the dough into a log 2-4 inches in width and around 12-14 inches in length. If your dough is too sticky, sprinkle a little flour on top. Bake the log for about 15 minutes. Remove it from the oven and allow it to slightly cool for about 5-10 minutes.
Using a serrated knife, cut your log diagonally about ¾-1 inch thick. I get anywhere between 16-18 biscottis. Arrange them back onto a sheet pan with parchment paper laying them flat and bake for an additional 15 minutes or until lightly brown. After they're done baking remove them from the oven and place them on a wire rack so they can continue to crisp up. If you wan't to take them over the top, dip them in chocolate and top with nuts, sesame seeds and flake salt, or just enjoy them as is.