Preheat and Prep: Preheat your oven to 350°F (175°C). Grease a 12×17-inch rimmed baking sheet (half-sheet pan) thoroughly with butter or non-stick cooking spray to ensure the cake releases easily after baking.
Combine Dry Ingredients: In a medium-sized mixing bowl, whisk together the all-purpose flour, granulated sugar, baking soda, baking powder, cinnamon, ginger, cloves, and salt until well combined and free of large lumps.
Mix Wet Ingredients: In a large bowl, beat the 4 eggs slightly. Add the vegetable oil and the pumpkin puree. Use a whisk or an electric mixer to blend these together until the mixture is smooth and uniform in color.
Create the Batter: Gradually add the dry ingredients into the wet pumpkin mixture. Stir or mix on low speed just until the flour disappears. Be careful not to overmix, as this can make the cake tough.
Bake the Cake: Pour the batter onto the prepared baking sheet and spread it evenly into the corners using a spatula. Bake for 25 to 30 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool completely in the pan.
Prepare Cream Cheese Frosting: While the cake cools, beat the softened cream cheese and butter together in a bowl until creamy. Add the vanilla extract and slowly mix in the powdered sugar one cup at a time until the frosting is light and fluffy.
Frost and Garnish: Once the cake is entirely cool, spread the frosting over the top in an even layer. If using, sprinkle the chopped pecans over the frosting for an added crunch and professional look. Slice into 24 squares and serve.