Cream the softened butter and granulated sugar until smooth and well combined.
Add the eggs and whisk until the mixture becomes lighter in color, about 3 minutes.
Add the lemon zest, all-purpose flour, baking powder, baking soda, and salt. Mix just until a dough forms.
Fold in the almonds until evenly distributed.
Divide the dough and shape it into even logs on a parchment-lined baking sheet.
Bake the logs until lightly golden and set.
Let the logs cool for 10–15 minutes, then slice them diagonally into about 1/2-inch-thick pieces using a serrated knife.
Arrange the slices cut-side down on the baking sheet and bake again until dry and crisp.
Let the biscotti cool completely. They will continue to crisp as they cool.
