Preheat the oven to 350°F and line a 12 cup muffin pan with cupcake liners.
Whisk the cake flour, baking powder, pumpkin pie spice, and salt together in a large bowl.
In a separate bowl, whisk the brown butter, brown sugar, eggs, and, vanilla together until combined. Then stir in the pumpkin puree.
Then stir in the flour mixture and mix until fully combined. The batter will be thin.
Pour about ¼ cup of batter into each cupcake liner (they should be about halfway full).
Bake at 350°F for 18-22 minutes or until a cake tester comes out clean.
Remove from pan and let cool on wire rack.
Let cupcakes cool completely before frosting.
Brown Sugar Swiss Meringue
Create a double boiler by bringing 1-2 inches of water to a simmer in a small saucepan.
In the bowl of a stand mixer (make sure your bowl is heat safe - stainless steel is best), whisk the brown sugar and cream of tartar into the egg whites then set the bowl over your double boiler. Do not let the bottom of the egg whites bowl touch the water.
Whisk the whites and sugar constantly until sugar is dissolved and mixture has thinned out (about 3-4 minutes). If using an instant thermometer, it should read about 160°F.
Place the bowl on the stand mixer and fit with the whisk attachment. On medium-high speed, beat the mixture until soft peaks form. Then increase the speed and beat on high until stiff peaks form and the meringue is no longer warm to the touch, at least 10-15 minutes.
If it’s still not reaching stiff peaks, stop the mixer, place the bowl in the fridge for 10 minutes, then return to the mixer and continue beating until stiff peaks form.
Frost cooled cupcakes. I used a Wilton 1M tip for these photos.
After frosting, use a culinary blow torch to lightly toast the meringue.
Notes
These cupcakes will last in the fridge for up to 3 days. However, they taste best when served at room temperature! I like to let them sit at room temperature for about an hour before serving.
To make brown butter, melt unsalted butter over medium heat, stirring frequently. Watch closely for the butter to develop brown specs and a nutty aroma. Once you start seeing brown specs, let cook for just a few seconds longer (watch very carefully or it will burn). Remove from the heat and pour into a small bowl so that it doesn't continue to cook. Set aside and let cool for about 20 minutes in the fridge until soft and pliable. Note: For every ½ cup (1 stick or 113g), you'll lose about 1 tablespoon (14g) to evaporation while cooking. So you can either add in an extra 1 tablespoon before browning, or if you're browning big batches, just make up the weight difference in your recipe with regular unsalted butter if needed.