Heat oven to 375 degrees F. Grease 9 x 9 x 2-inch square metal baking pan; dust with flour; tap out excess.

Gingerbread: Combine butter and fresh ginger in large heavy saucepan. Cook over medium heat until butter melts and ginger is very aromatic, 3 to 5 minutes. Stir in salt, cinnamon, allspice, ground ginger and pepper; cook 30 seconds. Remove from heat.

Stir in sugar, molasses and mustard until smooth. Mix in eggs and baking soda until mixture begins to foam. Immediately stir in flour and beat well. Mix in coffee until batter is smooth; it will be fairly thin. Pour batter into prepared pan.

Bake in 375 degrees F oven 40 to 45 minutes, until center springs back when lightly pressed with fingertip. Cool in pan on rack 10 minutes. Invert cake; remove pan. Turn right side up; let stand until warm. (Can be made several weeks ahead up to this point. Cool; wrap in plastic wrap, then in foil; freeze. Thaw overnight in refrigerator.)

Cut gingerbread into 12 pieces. Dust tops of gingerbread squares with confectioners' sugar, using designs cut out of stiff paper. Or if desired, beat cream in bowl until it just begins to hold shape. Add sugar, vanilla and ginger. Beat until soft peaks form. Refrigerate. Whip lightly just before serving.