Line a muffin tray with cupcake liners or spray it with a nonstick spray. Set aside.
Preheat oven to 350 F degrees.
Spray a baking sheet with oil and place pecans on it.
Toast the pecans at 350 F degrees for 6-7 minutes or till fragrant.
Take out of the oven and chop them coarsely. Set aside.
In a bowl whisk together all purpose flour, salt, baking soda, baking powder, cinnamon powder and pumpkin pie spice. Set aside.
In the steel bowl of your stand mixer or using your hand mixer beat together vegetable oil and both the sugars till well combined.
Add eggs, vanilla extract and mix till well combined.
Now add the pumpkin puree and mix.
Start adding the flour mix and alternate with buttermilk. Add the flour in 3 parts and buttermilk in 2 parts starting and ending with flour.
Mix till just combined. Do not overmix.
Fold in the chopped toasted pecans.
Fill the cupcake liners till 2/3 full with the batter.
Bake at 350 F degrees for 17 minutes or till a toothpick inserted in the center of a cupcakes comes out clean.
Cool cupcakes completely before frosting.
Chocolate Frosting
Using steel bowl of your stand mixer fitted with paddle attachment or using your hand mixer beat room temperature butter till smooth and creamy, around 3-4 minutes.
Now start adding confectioners sugar, 1/2 cup at a time. Beat at slow speed at first and once the sugar mixes in a little, beat at high speed for 30 seconds.
Add vanilla, unsweetened cocoa powder and mix till well combined.
Add heavy cream and beat till frosting is nice and smooth.
Frost the cooled cupcakes using the chocolate frosting.