Double Chocolate Chunk Biscotti

In a large mixing bowl, beat the butter and margarine with an electric mixer on medium speed for 30 seconds. Add the sugar, cocoa powder, and baking powder and beat until combined.

Beat in the eggs until smooth, then beat in as much of the flour as you can. Using a spoon, stir in the remaining flour along with the white chocolate and semisweet chocolate chunks.

Divide the dough in half. Shape each half into a 9-inch-long log and place the logs several inches apart on the prepared cookie sheet, flattening each slightly until about 2 inches wide.

Bake in a 375°F (190°C) oven for 20 to 25 minutes, or until a wooden toothpick inserted near the center comes out clean.

Cool the logs on the cookie sheet set on a wire rack for about 1 hour.

Using a serrated knife, cut each log diagonally into 1/2-inch slices. Arrange the slices cut-side down on the cookie sheet and bake again at 325°F (165°C) for 8 to 10 minutes per side, until crisp. Cool completely on a wire rack.