Preheat oven to 350 degrees. Line a large, heaving baking sheet with parchment paper. Combine flour, baking powder, and salt in a medium bowl. Stir to blend and set aside.
In another bowl, beat butter, sugar, eggs, and almond extract together. Mix in flour mixture and dried cranberries to form dough. Divide dough in half.
Using lightly floured hands, shape each half into a 1-inch log directly on the baking sheet. Whisk egg white and brush top and sides of each log.
Bake 30 to 35 minutes, until golden brown. Cool completely. Slice logs on a diagonal with a serrated knife into 1/2-inch pieces. Bake 10 to 12 minutes at 375 degrees on baking sheet without parchment. Turn biscotti over and bake 5 minutes longer.