Buttermilk Cupcakes for Everything

Ingredients

• 1¾ cups (238 g) all-purpose flour
• 2 teaspoons baking powder
• ½ teaspoon baking soda
• ½ teaspoon fine sea salt
• 10 tablespoons (140 g) unsalted butter, at room temperature
• 1 cup (200 g) granulated sugar
• 3 large eggs, at room temperature
• 1 large egg yolk, at room temperature
• 2 teaspoons pure vanilla extract
• ¾ cup (180 ml) buttermilk, well shaken and at room temperature
• 1 cup (226 g) unsalted butter, at room temperature, for the frosting
• 3 cups (360 g) confectioners’ sugar, sifted
• 2 teaspoons pure vanilla extract, for the frosting
• 2 to 3 tablespoons heavy cream or whole milk
• Pinch of fine sea salt, plus sprinkles or candied citrus for decorating (optional)

Instructions

1. If two muffin pans fit on the center rack, center a rack in the oven; otherwise position two racks to divide the oven into thirds. Preheat to 350°F (175°C). Line 18 muffin cups with paper liners.
2. Whisk the flour, baking powder, baking soda, and salt together in a medium bowl.
3. Using a stand mixer fitted with the paddle attachment or a hand mixer, beat the butter and sugar on medium speed for 3 to 4 minutes, scraping the bowl as needed, until very light and fluffy.
4. Add the eggs one at a time, beating for about 1 minute after each addition. Add the yolk and beat for 1 minute more, then mix in the vanilla. The batter may look slightly curdled; it will smooth out as the flour is added.
5. On low speed, add one-third of the flour mixture and mix just until it nearly disappears. Mix in half the buttermilk, then repeat with half the remaining flour, the remaining buttermilk, and finally the remaining flour. Stop as soon as the batter is evenly blended.
6. Divide the batter among the prepared cups, filling each about three-quarters full.
7. Bake for 19 to 21 minutes. If the pans are on separate racks, rotate them top to bottom and front to back at the 10-minute mark. The cupcakes are ready when the tops spring back and a tester inserted in the center comes out clean; they will remain pale.
8. Cool in the pans for 5 to 10 minutes, then transfer the cupcakes to wire racks and let them cool completely.
9. For the buttercream, beat the butter on medium-high speed for about 3 minutes, until pale and creamy. On low speed, gradually beat in the confectioners’ sugar. Add the vanilla, salt, and 2 tablespoons cream, then beat on medium-high for 2 to 3 minutes. Add the remaining cream if needed for a soft, pipeable texture.
10. Pipe or spread the buttercream over the cooled cupcakes. Finish with sprinkles or tiny pieces of candied citrus, if desired.