Position the oven rack in the center of the oven. Preheat the oven to 350°F. Line a 9 by 3-inch round cake pan or a 9 1/2 inch springform pan with a circle of parchment paper.
Peel, slice, and chop the ginger very fine with a knife (or use a grater). Mix together the molasses, sugar, and oil. In another bowl, sift together the flour, cinnamon, cloves and black pepper.
Bring the water to the boil in a saucepan, stir in the baking soda, and then mix the hot water into the molasses mixture. Stir in the ginger.
Gradually whisk the dry ingredients into the batter. Add the eggs, and continue mixing until everything is thoroughly combined. Pour the batter into the prepared cake pan and bake for about 1 hour, until the top of the cake springs back lightly when pressed or a toothpick inserted into the center comes out clean. If the top of the cake browns too quickly before the cake is done, drape a piece of foil over it and continue baking.
Cool the cake for at least 30 minutes. Run a knife around the edge of the cake to loosen it from the pan. Remove the cake from the pan and peel off the parchment paper.