Preheat the oven to 350F (180C). Lightly grease a 10x15 inch (24x38 cm) jelly roll pan, or line with parchment paper.
Whisk together the flour, cinnamon, ginger, nutmeg, ground cloves, baking powder, baking soda and salt. Set aside.
In a separate large bowl, whisk together the oil, sugars, eggs, vanilla extract, orange zest and pumpkin puree until there are no lumps of brown sugar or pieces of egg.
Gently whisk the dry ingredients into the wet ingredients. The mixture will be thick. Be sure to stop whisking once you no longer see streaks or lumps of dry ingredients.
Pour/spoon the batter into the prepared pan and smooth into an even layer.
Bake in the preheated oven for about 25-30 minutes, or until the top looks set and an inserted toothpick comes out clean.