Preheat the oven to 350°F. Line a baking sheet with parchment paper.

In a medium-sized bowl, beat the butter, sugar, salt, vanilla, and baking powder until the mixture is smooth and creamy.

Beat in the eggs; the batter may look slightly curdled. Turn down the mixer speed to low then add the flour, stirring until smooth; the dough will be sticky.

Divide the dough in half and plop each half onto the prepared baking sheet. Shape each half into a log roughly 9½” x 2″ logs, about ¾” tall. Smooth the tops and sides using a wet spatula (or your hands).

Bake the dough for 25 minutes. Remove from the oven.

Very lightly sprinkle the top and sides of the logs with a little water. Softening the crust just this little bit will make slicing the biscotti much easier. Reduce the oven temperature to 325°F.

Wait 5 minutes, then using a sharp serrated knife, cut the logs crosswise into ½” to ¾” slices. For longer, but fewer biscotti, cut the logs on the diagonal. As you’re slicing, be sure to cut straight up and down, perpendicular to the pan.

Set the biscotti, cut edge down, on the prepared baking sheet. Return the biscotti to the oven, and bake for 25 to 30 minutes, until they feel very dry and are beginning to turn golden. They’ll still feel a tiny bit moist in the very center, if you break off a piece; but they’ll continue to dry out as they cool.

Remove the biscotti from the oven, and transfer them to a rack to cool.