Preheat oven to 350°F. Mix sugar, flour, ginger, cinnamon, nutmeg, allspice, cloves, and baking powder in large bowl. Mix well.
In a separate bowl, combine butter and molasses. Add eggs one at a time until incorporated.
Divide dough in half. Shape each half into a 12-inch log. Place logs 3 inches apart on wax paper-lined baking sheet. Flatten logs slightly.
Bake 23-28 minutes or until tops are cracked. Remove from oven. Coll for about 20 minutes on baking sheet. Reduce oven to 300°F. Gently place logs onto a cutting board. Cut into 1-inch diagonal slices with serrated knife. Place cut-side down, onto wax paper-lined baking sheets (feel free to re-use the wax paper you just baked the "logs" on).
Return to oven. Bake 10-12 minutes; turn to side. Continue baking 8-10 minutes or until biscotti are dry. Cool completely.