This pumpkin cake is soft and moist, packed with warm spices, and topped with cinnamon sugar. This single layer cake can be whipped up in minutes with pantry staples.
Preheat oven to 350°F with a rack in the center of the oven.
Whisk flour, baking powder, baking soda, salt, pie spice, and cinnamon until combined. Set aside.
In a large bowl, whisk pumpkin, brown sugar, granulated sugar, sour cream, oil, eggs, and vanilla. Add the flour mixture and whisk until just combined (don't overmix). Tap the excess batter off the whisk and use a rubber/silicone spatula to stir the batter a couple of times, scraping the sides and bottom of the bowl.
Grease an 8x8 square metal baking pan and pour the batter into the pan. Tap the pan gently but firmly on the countertop a couple times to remove air bubbles.
Combine the sugar and cinnamon for the topping. Sprinkle over the top of the cake batter. Bake for 28-33 minutes, until a toothpick inserted into the center of the cake comes out clean. Note: If your toothpick poke makes a visible hole just slide of some the excess cinnamon sugar on top of the cake over the hole. Place the pan on a wire rack to cool completely.
Notes
Pan recommendations: Use a metal/aluminum pan if possible; for cakes and bars this is always my preference. This cake can be baked in 8x8 (pictured) or a 9x9. The 9x9 will produce a thinner cake and you will need to reduce the bake time by 5-10 minutes.Topping: The day you bake this cake the cinnamon sugar topping will be crackly and a little crunchy. In the days following the topping will soften from the moisture from the cake.Serving: Serve this cake at room temperature. It can be served as is or with honey butter (highly recommended).Storage: Store this cake at cool room temperature for up to 2 days or refrigerated for up to 4 days.