Preheat the oven to 350F degrees and place liners in a muffin tin (NOTE: If you only have one 12-cup muffin pan, then you'll need to make these in two batches. Set aside.
In a large mixing bowl beat butter and sugar for 2-3 minutes until combined with a stand or hand mixer.
Once that is beaten, add in pumpkin puree, eggs, and vanilla. Beat again until combined. Set aside.
Sift all the dry ingredients in a separate bowl (flour, baking soda, baking powder, pumpkin pie spice) and add half into the pumpkin mixture.
Slowly fold in with a rubber spatula. Once that is just combined add in remaining dry ingredients and mix until no more flour appears. This is so you will not over mix.
Divide batter into muffin tins, filling only ⅔ full to avoid spilling.
Bake for 20-22 minutes until a toothpick comes out clean.
In a stand mixer or hand mixer use a paddle attachment to whip the butter and 4 cups of powdered sugar for 1 minute. Add in milk, salt and pumpkin spice. Beat on low for 30 seconds and then medium high for 2-3 minutes.
Add 1-2 more cups of powdered sugar depending on what consistency you like for your buttercream. I added a total of 5 cups and it came out perfect for topping a cupcake.
If desired, place the buttercream into a piping bag with an Ateco 808 (or a Wilton 1A) round tip. On the cooled cupcakes, pipe the frosting, beginning in the center, and go round and upward on top.
Top the cupcakes with a mellow cream pumpkin candy.
Notes
These make a large batch you can halve this if you'd like.
These can be frozen, see my tips above on how to do that.
Make sure your cupcakes are completely cooled before frosting.