Preheat oven to 350F. You will need a 15 x 10-inch baking pan with sides at least 1-inch high. If you want to remove your cake from the pan at all, line the bottom with parchment, leaving an overhang over the sides to use as handles to lift it out.
In a large bowl with an electric mixer or the bowl of a stand mixer fitted with a paddle attachment, beat together the eggs, sugar, oil and pumpkin until light and fluffy.
In a medium bowl, whisk together well the flour, cinnamon, salt, baking soda and baking powder. Add to the pumpkin mixture and mix until thoroughly combined.
Spread batter into an ungreased 15 x 10-inch baking pan with sides at least 1 inch high.
Bake in preheated oven for 25-30 minutes, or until a tester inserted in the middle comes out clean.
Remove from oven and allow to cool completely in the pan before frosting.
Once cooled, prepare the frosting by beating together the cream cheese and butter until light and fluffy. Add the vanilla and mix in. Add the icing sugar a bit at a time, beating until the frosting is smooth.
Be sure to read the "Cook's Notes" in the original post, for more tips, options, substitutions and variations for this recipe!