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, 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.
Store cupcakes in the fridge for up to 3 days.Brown the butter: In a small saucepan, melt butter over medium heat. Once melted, stir frequently and watch closely for the formation of brown specs on the bottom of the pan and a nutty aroma. Once you see brown specs, stir for just a few more seconds (it browns super quickly). Remove from the heat and immediately pour into a different bowl to prevent it from burning. Let cool for at least 10 minutes.