• Preheat the oven to 350°F and line a baking sheet with parchment.
• Cream together butter, granulated sugar, brown sugar, vanilla, lemon zest, and juice until soft and creamy. Add eggs, one at a time, until mixed.
• Add flour, baking powder, and salt; mix until smooth. Fold in almonds. The dough will be sticky.
• Drop dough onto the prepared baking sheet. Divide in half and shape into two 10 x 3 inch rectangles.
• Bake in the oven for 25 minutes, or until a toothpick inserted in the center comes out clean. Let cool; about 15 minutes. Using a serrated knife cut crosswise into ½-inch to ¾-inch slices. (If you like longer slices, cut loaf on the diagonal).
• Turn each slice to its side and return to the baking sheet. Bake for an additional 10 minutes. Flip the cookies to the other side and bake for an additional 8 to 10 minutes, or until golden brown. The biscotti should feel dry to the touch and be a light golden brown. They will continue to dry as they cool.

For the Glaze

• Mix the confectioners' sugar and lemon juice until smooth and drizzleable. To thicken, add a bit more confectioners' sugar; to thin, add a drop of lemon juice.