In a medium bowl, whisk together the flour, baking powder, and salt.
In a large bowl, mix together the sugar, butter, and almond extract until just smooth. One at a time, beat in the eggs. Add the flour mixture and almonds and mix until just incorporated (do not overmix). Refrigerate the dough, covered, until firm enough to handle, 30 to 60 minutes.
Heat oven to 350° F. Divide the dough in half and shape into two 12-by-2-inch logs (about ¾ inch thick). Place on a parchment-lined baking sheet. Bake until just golden around the edges and firm to the touch, 25 to 30 minutes. Transfer the loaves to a rack and cool for 15 minutes.
Using a serrated knife, cut the logs into ½-inch-thick slices. Arrange in a single layer on the baking sheet. Bake until dry and crisp, 18 to 22 minutes. Cool completely on the baking sheet. Store the biscotti in an airtight container at room temperature for up to 2 weeks.