This is the BEST pumpkin cake I've ever tried – super moist, rich, and packed with intense pumpkin spice.
Preheat the oven to 177 °C (350 °F) and grease the 9×13‑inch baking pan. Use a metal or glass baking sheet for this.
In a large bowl, combine flour, baking powder, baking soda, salt, cinnamon, and pumpkin pie spice. In a second bowl, whisk oil, eggs, brown sugar, granulated sugar, pumpkin puree, and vanilla extract until well blended. Add the wet mixture to the dry ingredients and beat with a hand or stand mixer until a thick batter forms.
Evenly pour the batter into the prepared pan and bake in the preheated oven for 30‑36 minutes, until a toothpick inserted in the centre comes out clean. If the top browns too quickly, loosely cover with aluminum foil.
Remove the cake from the oven, place it on a cooling rack and let it cool completely (about 45 minutes). Then let the cake rest in the refrigerator for about 30 minutes so it’s easier to slice.
For the frosting, beat the cream cheese and butter in a large bowl with the hand or stand mixer on high speed until creamy. Mix in powdered sugar, vanilla extract, and salt; first 30 seconds on low speed, then 2 minutes on high speed. If the frosting is too soft, add an extra ¼ cup powdered sugar. Spread the frosting over the fully cooled cake and refrigerate for at least 30 minutes to set.
Wrap the finished cake airtight and store in the refrigerator for up to 5 days.