Preheat oven to 350°F (175°C). Grease and flour a 15x10x1-inch jelly roll pan.

In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon, nutmeg, ginger, and salt.

In a large bowl, beat the eggs and sugar until light and fluffy. Slowly mix in the oil, then the pumpkin puree.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.

Pour the batter into the prepared pan and spread evenly. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.

Let the bars cool completely in the pan on a wire rack.

To make the frosting, beat the softened cream cheese and butter until smooth. Add the vanilla. Gradually beat in the powdered sugar until smooth and fluffy.

Spread the frosting over the completely cooled bars. Cut into squares and serve.