Toast your almonds by placing them in a skillet over medium heat until the almonds are fragrant and golden brown. Stir them frequently so they brown on all sides and remove any that brown quicker than others. It should take about 3-5 minutes. Remove the toasted almonds from the heat, wrap them in a kitchen towel, and crush them with a meat mallet.
Preheat your oven to 350˚F and line a baking sheet with parchment paper.
Add the crushed almonds, flour, baking powder, and salt to a large bowl and stir to combine. Set aside.
Using a stand mixer, beat the eggs, sugar, almond extract, anise extract, and optional anise seeds on medium speed until light and fluffy, about 5 minutes. Add the flour mixture a little at a time. If the mixer begins to strain, work the rest of the flour in with a wooden spoon or your hands. The dough will be firm and sticky.
Gather the mixture into a log shape and place it in the center of the prepared baking sheet. Wet your hands and pat the dough into a 4 x 12 inch dome shaped slab.
Bake in preheated oven for 50-60 minutes, or until brown and firm when you touch the top with your finger. Remove the biscotti from the oven and let it cool. Reduce your oven heat to 300˚F.
Once the biscotti slab is cool enough to handle, transfer it to a cutting board. Use a serrated knife and slice into 1/2-inch wide biscotti. Place slices cut side down on the baking sheets, and bake again until desired crispness. If you want softer biscotti, bake about 8 minutes on each side. If you are aiming for harder biscotti that will stand up to dunking, bake about 20 minutes on each side. Let the biscotti cool completely on the baking sheets or a wire cooling rack. Store in a metal tin. Makes about 16 biscotti.