RECIPE PREP: Crack the eggs into a bowl and add the lemon ZEST. In another bowl, whisk together the flour, baking powder and salt. Prepare the egg wash.
PAN PREP: Spray heavy duty baking sheets with non-stick spray, rub with butter (used the wrappers from the recipe) and dust with flour, knocking off all the excess. Keep this excess to roll the biscotti logs out. UPDATE 12/2017: Aunt Dot has asked me to update pan prep to say that she now simply lines the baking sheets with baking parchment. Feel free to continue old school but parchment can be reused through the entire batch of biscotti dough.
Combine the butter and sugar. Add the anise oil and vanilla. Cream together for 15 minutes. Scrape the bowl often; the mixture will be light and fluffy.
Add the eggs one at a time. Continue to scrape the bowl often. Add the lemon juice.
With the mixer on low speed, begin adding the flour, a large scoop at a time. Continue to scrape down the sides. When there is about a cup or so of flour left, add the almonds to the flour and toss to coat. Add this to the batter and mix to combine. If the dough is too wet, add a cup or so of extra flour but don't make it dry. This is a very soft dough.
Remove the bowl from the mixer and scoop about 1 cup of the dough at a time onto a floured counter. Roll the dough into a log about 2 inches in diameter and about 2/3 the length of your baking sheet. Transfer the dough roll onto the pan, giving each roll about 6 inches of space. Pat the rolls along the length of the roll so that it is the thickness of the nuts. This will leave ridges on the dough which then need to be patted out to a smooth flat dough.
Brush each slab of dough with the egg wash. Be careful not to get drips onto the pan which will burn.
Bake at 350 for about 20 minutes until pale golden. If not pale golden, add 5 minutes at a time until pale golden only.
Remove the pans from the oven and slide the biscotti slabs with a large spatula to release from the pan. Cut on the bias with a pizza wheel and lay them on their sides, they can be close together to consolidate pans.
Bake an additional 20 minutes or until light golden brown, adding 5 minutes at a time until your desired color. Remove to a cooling rack and cool overnight. Store in a cool dry place. NOTE: If you have a gas stove with a pilot light, you can turn off the oven after the initial cooking phase and return the sliced, consolidated biscotti to the warm oven overnight. Aunt Dot swears by this newest method.