In a mixing bowl, sift together all of your dry ingredients. Flour, baking powder, baking soda, cinnamon and pie spice. Mix well to combine.
Using a stand or hand mixer on a low setting, add in the brown and granulated sugar. Once incorporated, slowly add the pumpkin puree, then eggs, vanilla and oil. Continue to mix on low until the oil has fully blended with the batter.
If you are making a cake, divide 2 cups of batter into a 6 inch spring form pan per each layer. Approx. 1/3 Cup of batter per cupcake. Bake at 350 degrees. Cake is done when a toothpick inserted in the center of the cake comes out clean. I used a 1.25oz disher (icecream scoop) to create the uniform shape and size of my whoopie pies. Just spoon the batter out onto a parchment lined pan and bake until lightly browned. Let the cake cool fully before frosting.