Preheat your oven to 175°C (350°F). Lightly grease your 9x13 inch baking pan or line it with parchment paper for easy removal.
In a large bowl, whisk together the flour, baking powder, salt, cinnamon, and nutmeg. This ensures an even distribution of spices and leavening agents.
In another bowl, combine the pumpkin, brown sugar, eggs, and melted butter. Whisk until the mixture is smooth, fragrant, and slightly thickened.
Gradually fold the dry ingredients into the wet mixture using a spatula, mixing gently until just combined. Be careful not to overmix to keep the batter tender.
Pour the batter into your prepared pan, spreading it evenly with a spatula. Tap the pan lightly on the counter to settle the batter and release any air bubbles.
Bake in the preheated oven for 25-30 minutes, or until the top is golden, cracks slightly, and a toothpick inserted into the center comes out with moist crumbs.
Remove the pan from the oven and let the pumpkin bars cool in the pan on a wire rack for at least 15 minutes to set.
If using cream cheese frosting, spread it evenly over the cooled bars. Allow the frosting to set slightly before slicing.
Use a sharp knife to cut into squares, revealing the moist, tender crumb speckled with warm spice. Serve and enjoy the cozy aroma and delightful flavor.
