Preheat the oven to 350°F. Lightly grease a large, rimmed 13x18-inch baking sheet (aka a half sheet pan).
In a large bowl, mix the pumpkin, sugar, oil, and eggs.
1 (15-ounce) can pumpkin puree, 2 cups granulated sugar, 1 cup vegetable oil, 4 large eggs
Add the flour, baking powder, baking soda, salt, and cinnamon. Stir to combine.
2 cups (282g) all-purpose flour, 1 teaspoon baking powder, 1 teaspoon baking soda, 1/2 teaspoon salt, 2 teaspoon ground cinnamon
Pour the batter into the prepared pan and spread in an even layer. Bake for 20-25 minutes until the cake springs back lightly to the touch and has barely started to pull away from the sides of the pan. Do not overbake!
Remove cake from oven and let cool.