Lightly grease a large cookie sheet; set aside. In a large mixing bowl, beat butter with an electric mixer for 30 seconds. Add sugar, cocoa powder and baking powder. Beat until combined, scraping sides of bowl occasionally. Beat in eggs until combined. Beat in as much of the flour as you can with the mixer. Stir in any remaining flour. Stir in chocolate pieces and dried cranberries or cherries.

Divide dough in half. Shape each dough portion into a 9-inch-long roll. Place rolls on prepared cookie sheet, 5 inches apart; flatten logs slightly until about 2 inches wide.

Bake in a 375 degree F oven about 20 minutes or until a wooden toothpick inserted near center comes out clean. Cool on cookie sheet for 1 hour. (For easier slicing, wrap cooled rolls in plastic wrap and let stand overnight at room temperature.)

Use a serrated knife to cut each roll diagonally into 1/2-inch slices. Place slices, cut sides down, on an ungreased cookie sheet. Bake in a 325 degree F oven for 8 minutes. Turn slices over and bake for 7 to 9 minutes more or until dry and crisp. (If baking slices after cooling the logs only 1 hour, you may need to bake 1 to 2 minutes longer per side.) Transfer to a wire rack and let cool.

If you like, drizzle cooled biscotti with Powdered Sugar Icing. Makes about 28 cookies.

In a small bowl, combine 1 cup powdered sugar, 1 tablespoon milk and 1/2 teaspoon vanilla. Stir in additional milk, 1 teaspoon at a time, until icing reaches a drizzling consistency.