Preheat the oven to 350°F. Lightly oil a 9x13 inch baking pan.
In a medium size bowl combine the flour, baking soda, ginger, cinnamon, cloves, and salt. In a large bowl whisk together the oil, eggs, pumpkin, molasses and sugar until smooth.
Dump the dry ingredients into the pumpkin mixture and whisk to combine. Pour in the boiling water and whisk until smooth. Whisk in the chopped candied ginger, if using.
Pour into the prepared pan and bake for about 30 minutes until done; test for doneness by inserting a wooden skewer into the center and if it comes out clean, the gingerbread is done.
Cool completely in the pan on a wire rack. Cut into squares and serve.
Notes
The candied ginger is optional, but I highly recommend it for both the flavor and the texture. It's a great ingredient as it keeps for a long time in the pantry.