Preheat the oven to 350°F (175°C). Line a 9 x 13-inch baking pan with parchment paper, leaving overhang on two sides, and lightly grease any exposed corners.

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

In a large bowl, whisk the eggs, granulated sugar, and brown sugar until smooth. Whisk in the oil, pumpkin puree, and 2 teaspoons vanilla extract.

Add the dry ingredients to the pumpkin mixture and fold gently with a rubber spatula until no dry flour streaks remain. Do not overmix.

Spread the batter evenly in the prepared pan. Bake for 26–32 minutes, about 30 minutes on average, until the center springs back lightly and a toothpick inserted in the center comes out clean or with a few moist crumbs.

Let the bars cool completely in the pan on a wire rack for approximately 60 minutes before adding frosting.

For the frosting, beat the softened butter until smooth. Add the cream cheese and mix just until combined. Gradually mix in the powdered sugar, then add 1 teaspoon vanilla extract and a pinch of salt. Avoid overbeating.

Spread frosting over the completely cooled bars. Scatter Halloween sprinkles on top and add two edible candy eyes to each bar if using.

Lift the slab from the pan using the parchment overhang and slice into 24 bars (4 rows by 6 columns). Refrigerate leftovers in an airtight container.