Preheat the oven to 350º F. Line a muffin pan with 12 muffin liners.

In a bowl combine the flour, baking powder, baking soda, salt, cinnamon, and pumpkin pie spice. Mix well to combine.

In a separate bowl, combine the brown sugar and butter, beat together using an electric mixer until creamy, 1 minute.

Add in the eggs, one at a time, beating the mixture after each one.

Add in the pumpkin puree,  mixing by hand with a spatula.

Add half of the flour mixture to the wet ingredients, do not dump it in, rather take spoonfuls of the flour mixture and gently shake it over the wet ingredients, as if you were sifting in the flour. Fold in the mixture until no flour remains. Repeat with the other half of the flour, folding it in and scraping the sides and bottom of the bowl to incorporate everything.

Evenly divide the batter among the muffin pan, filling each 2/3 full. Bake for 15-18 minutes or until a toothpick inserted in the center comes out clean.

Allow the cupcakes to cool for about 3 minutes in the pan, then take them out and allow them to cool on a cooling rack. Allow the cupcakes to cool completely before adding the frosting.

Place room temperature butter (and vegetable shortening if using) in a mixing bowl. Beat using an electric mixer until smooth, 1 minute.

Add in the pumpkin puree and pumpkin pie spice. Mix using a spatula.

Add in the powdered sugar, 1 cup at a time, mixing with a spatula at first so the powered sugar doesn’t puff up everywhere. Once all of the powdered sugar is incorporated, beat the buttercream using an electric mixer, 1-2 minutes or until smooth.

Transfer frosting to a piping bag and pipe the frosting onto the cupcakes.