Combine flour, baking soda, cinnamon, ginger, allspice, cloves, and pepper.
In another bowl cream the butter and sugar.
Add vanilla and molasses.
Add flour mixture and mix until combined.
Divide dough in half an press each half into a rectangle that is about 14 inches long and 4-5 inches wide. Score each into 16 equal biscotti.
Bake at 350F for about 30 minutes or until slightly firm to the touch. Let cool for 10 minutes before cutting on score lines. Place cut side down on baking sheet and bake for 10 minutes more on each side until crisp.
Dust with powdered sugar after baking.