Preheat oven to 350 degrees.
Put cupcake liners in the muffin pan.
Put the 1⁄2 cup of chopped pecans in a bowl.
Add flour, baking powder, baking soda, salt, cinnamon, allspice, ginger, nutmeg, and cloves in a large bowl.
Whisk to blend. Set aside.
Add the oil, eggs, brown sugar, pumpkin puree, and vanilla in a large bowl. Use an electric mixer to mix all ingredients.
Slowly add the wet ingredients to the dry ingredients, continue to beat while adding until completely combined. (The batter will be smooth.) Set aside.
Whisk the oil, eggs, brown sugar, pumpkin, and vanilla extract together until combined.
Pour the wet ingredients into the dry ingredients and use a mixer until completely combined. (Batter will be thick.)
Use an ice cream scoop to measure the batter to go into the paper-lined muffin tins. (Fill 2⁄3 full)
Bake at 350 degrees for 20-22 minutes. (Check by inserting a toothpick in the center comes out clean.)
Remove from the oven when done and set aside to cool completely before frosting.