Preheat the oven to 350°F and grease a 9x9-inch baking dish*. Line the bottom and two of the sides with a sheet of parchment paper, leaving a 1-inch overhang over the sides.

In a large bowl, whisk together the pumpkin puree, eggs, brown sugar, cane sugar, vegetable oil, milk, and vanilla extract.

In a medium bowl, whisk together the flour, pumpkin pie spice, baking powder, baking soda, and salt.

Add the dry ingredients to the wet ingredients and mix until just combined. Transfer the batter to the prepared pan and smooth the top.

Bake for 45 to 50 minutes, or until the top springs back to the touch and a toothpick inserted comes out clean. Place the pan on a wire rack to cool to room temperature.

Once cool, top with cream cheese frosting, if desired. Slice and serve.