Preheat the oven to 350°F.
Slightly grease one large baking sheet (approx. about 18" x 13"), or line the sheet with parchment.
Take a medium-sized bowl. And butter, salt, sugar, zest, almond extract, and baking powder and beat to a smooth and creamy mixture.
Add the lemon juice and eggs and beat some more until the batter looks somewhat curdled.
Switch mixture to low power and add flour; stir until smooth. The final dough should be sticky.
Spread the dough onto the pre-prepared baking sheet and shape it like a log about 13" long, 3" wide, and 3/4" thick.
Using a wet spatula or bowl scraper, straighten the log and smooth out the top and sides.
Place the smoothed dough in the oven and bake for 25 minutes.
Remove from the oven and cool for 10 to 25 minutes. Then, reduce oven heat to 350°F.
Use a spray bottle containing water at room temperature to lightly spray the entire log, thoroughly covering all sides and the top. This softens the crust and makes it easier to slice the biscotti.
After about 5 minutes, use a serrated knife and cut the log crosswise into slices measuring half an inch. Make sure to cut evenly; otherwise, the biscotti might be thicker at the top and topple over during the second bake.
Place the sliced biscotti on the prepared baking sheet and return it to the oven for 30 to 35 minutes. Bake till they feel extremely dry and begin to turn golden around the edges.
Remove from the oven, and transfer to a rack to cool.