Preheat oven to 350°F.
Line cupcake pans with cupcake wrappers (this recipe makes 18 cupcakes).
In a large bowl, mix together vegetable oil, brown sugar, granulated sugar, eggs, and vanilla just until combined.
½ cup vegetable oil, ½ cup brown sugar, ¼ cup granulated sugar, 2 large eggs, 2 teaspoons pure vanilla extract
Add pumpkin puree to wet ingredients and mix to combine.
1 ½ cups pumpkin puree
In a separate medium bowl, whisk together flour, pumpkin pie spice, cinnamon, baking powder, baking soda, and salt.
1 ⅓ cups all-purpose flour, ½ tablespoon pumpkin pie spice, 1 teaspoon cinnamon, 1 teaspoon baking powder, ½ teaspoon baking soda, ½ teaspoon salt
Add dry ingredients to wet ingredients and mix just until combined. Scrape down sides of bowl.
Lightly beat in buttermilk.
2 tablespoons buttermilk
Fill cupcake pans about ¾ full of cupcake batter.
Bake for 20-22 minutes or until toothpick inserted in middle comes out clean.
Cool completely before frosting.