Addictive even on their own, these tiny, vanilla-infused cupcakes are thoroughly irresistible when slathered with Salted Caramel Frosting. Whip some up for your next birthday party; they’ll appeal to both adults and kids.
Heat the oven to 350°F and arrange a rack in the middle. Line 2 (12-well) muffin pans with paper liners. Alternatively, coat the wells with butter; set aside.
Combine flour, baking powder, and salt in a medium bowl and whisk to aerate and break up any lumps; set aside.
Place butter in the bowl of a stand mixer fitted with the paddle attachment and beat on medium-high speed until very light in color, about 3 minutes. Add sugar and vanilla seeds (if you’re using vanilla extract instead, you’ll add it later), and continue beating until the mixture is airy, about 3 minutes.
Scrape down the paddle and the sides of the bowl, turn the mixer to medium speed, and add the egg whites one at a time, beating well after each addition. Then add the eggs one at a time, beating well after each addition.
Add the milk (and vanilla extract, if you’re using it in place of seeds) and mix until combined (the mixture will look curdled, but it’s not). Scrape down the sides of the bowl. Reduce the speed to low, add the reserved flour mixture, and mix until just combined, about 15 seconds.
Fill the muffin wells about halfway and bake until the cupcakes are golden brown and a toothpick inserted into the center comes out clean, about 18 minutes. Set the pans on a wire rack and let cool for 5 minutes. Remove the cupcakes from the pans and let cool completely before frosting.