Preheat oven to 350 degrees F and fill a cupcake tin with liners (you will either need to bake them in two batches, or use two pans). Set aside.
Whisk together the cake flour, baking soda, baking powder, salt, and pumpkin spice. Set aside.
192 grams cake flour, ½ teaspoon baking soda, ¾ teaspoon baking powder, ½ teaspoon fine sea salt, 2 teaspoons pumpkin spice
Start with one cup of pure pumpkin puree. Pumpkin puree is incredibly watery and the moisture content varies brand to brand, so we want to make sure you have enough.
Spread the pumpkin puree into a smooth layer on a cutting board. Gently press a stack of paper towels against the pumpkin puree so the paper towels absorb the liquid from the pumpkin. Scrape into a pile, spread it out again, and repeat this process until the pumpkin feels pretty dry & you can shape it into a ball with your hands. Use around 65 grams or roughly 1/4 cup of the dried pumpkin. You might have left over, but you will not need it.
240 grams pumpkin puree
Separately, beat together the unsalted butter, oil, and sugar until combined & fluffy.
57 grams unsalted butter, 50 grams vegetable oil, 200 grams granulated sugar
Add the eggs & vanilla and mix well, then add the dry ingredients and beat until almost combined but with a few streaks of flour still remaining.
2 eggs, 1 tablespoon vanilla bean paste or extract
Add the sour cream & dried pumpkin purée and beat until almost combined. Then, stream in the milk & beat until a smooth batter forms.
120 grams full-fat sour cream or yogurt, 60 grams whole milk
Fill each cupcake liner about half way. Bake for 12-15 minutes until risen and fluffy but still soft looking on top. A toothpick inserted into the center should come out clean or with a few moist crumbs.
While the cupcakes cool, make the cream cheese buttercream. Beat the butter on medium speed until creamy. Add the cream cheese and beat on medium speed until combined & smooth. Add half of the powdered sugar and beat on low-medium speed until combined. Then add the salt, vanilla, and the other half of the powdered sugar and beat until combined.
226 grams unsalted butter, 8 oz full-fat cream cheese, 360 grams powdered sugar, 1 pinch salt, ½ tablespoon vanilla bean paste or extract
Once the cupcakes have cooled completely, frost with a piping bag (for ease!) or with a knife, offset spatula, etc., and enjoy!