Preheat your oven to 350°F (175°C) and line a standard 12-cupcake pan with cupcake liners.

In a large mixing bowl, cream together the softened unsalted butter and granulated sugar until light and fluffy.

Add the egg, egg yolk, and vanilla extract to the butter-sugar mixture and mix until well combined.

Mix in the whole milk, sour cream, and pumpkin puree until the batter is cohesive.

In a separate bowl, whisk together the all-purpose flour, black cocoa powder, pumpkin pie spice, baking powder, baking soda, and salt.

Slowly add the dry ingredients to the wet mixture, mixing on low speed until just combined.

Fill the cupcake liners about three-quarters full with the batter.

Bake in the preheated oven for 17-19 minutes, checking for doneness with a toothpick.

Let the cupcakes cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.

Prepare the dried pumpkin by spreading ½ cup of canned pumpkin puree on a plate and dabbing away excess moisture until it reduces to ¼ cup.

In a medium bowl, beat the softened unsalted butter until it's pale and fluffy.

Combine the cold cream cheese with the beaten butter until well blended.

Incorporate the dried pumpkin puree and pumpkin pie spice into the mixture, blending until smooth.

Gradually mix in the sifted powdered sugar, increasing speed until the frosting is light and fluffy.

Transfer the frosting into a piping bag and pipe a generous swirl onto each cooled cupcake.