Preheat oven to 375°.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, sugar, baking powder, and salt in a large bowl. Place almonds in a food processor; pulse 10 times. Stir nuts into flour mixture.
Combine eggs and extract, stirring well with a whisk. Add egg mixture to flour mixture, stirring just until blended (dough will be crumbly). Turn dough out onto a lightly floured surface; knead lightly 7 or 8 times. Divide dough into 2 equal portions. Shape each portion into a 6-inch-long roll. Place the rolls 6 inches apart on a baking sheet coated with cooking spray, and pat to 1-inch thickness. Bake at 375° for 25 minutes or until lightly browned. Cool for 5 minutes on a wire rack.
Cut each roll crosswise into 12 (1/2-inch) slices. Stand slices upright on baking sheet. Bake 14 minutes (the cookies will be slightly soft in the center but will harden as they cool). Remove from baking sheet, and cool completely on a wire rack.