1. Preheat oven to 350 degrees and grease a 9×13 inch glass baking pan.
2. In a large bowl whisk the flour, baking powder, baking soda, salt, cinnamon, and pumpkin pie spice. Set aside.
3. In another bowl whisk the oil, eggs, brown sugar, granulated sugar, pumpkin, and vanilla extract until well combined. Pour the wet ingredients into the dry ingredients and use a mixer or whisk until completely combine.
4. Pour batter into the prepared pan. Bake for 30-35 minutes. Baking times vary, so keep an eye on it. The cake is done when a toothpick inserted in the center comes out clean.
5. Remove the cake from the oven and set the entire pan on a wire rack. Allow to cool completely.

Make the Frosting

1. In a large bowl using a handheld or stand mixer fitted with a paddle or whisk attachment, beat the cream cheese and butter together on high speed until smooth and creamy.
2. Add 3 cups powdered sugar, vanilla, and salt. Beat on low speed for 30 seconds, then switch to high speed and beat for 2 minutes. Spread the frosting on the cooled cake. Refrigerate for 30 minutes before serving. This helps set the frosting and makes cutting easier. Cover leftover cake tightly and store in the refrigerator for 5 days.
3. MAKE AHEAD INSTRUCTIONS: Prepare cake through step 5. Cover the cake tightly and refrigerate for up to 2 days or freeze up to 3 months. Bring to room temp, make the frosting, frost, and serve.