Preheat the oven to 350 degrees. Grease and flour a baking pan and set aside.
In a bowl combine the flour with the baking powder, sugar, salt, pumpkin pie spice mix, cinnamon, and nutmeg. Set aside.
In a separate bowl whisk together the oil, eggs, pumpkin puree, and vanilla extract.
Pour half the wet ingredients into the dry ingredients and beat until incorporated. Add the rest of the wet ingredients and beat on high speed for 3 minutes.
Pour the batter into the prepared baking pan and bake for 30 minutes or until done.
Remove from the oven and let cool completely before frosting.
While the cake is cooling you can prep the frosting. In a bowl beat all the ingredients together on medium speed until light and creamy.