• Preheat oven to 325F.
• Line standard muffin tins with paper liners
• Whisk together the flour, baking powder and salt
• With an electric mixer on medium-high speed, cream butter and brown sugar until pale fluffy
• Add eggs, one at a time, beating until each is incorporated, scraping down sides of bowl as needed
• Add flour mixture in three batches, alternating with two additions of buttermilk, and beating until combined after each
• Divide batter evenly among lined cups, filling each three-quarters full
• Bake, rotating tins halfway through, until golden brown and a cake tester inserted in centers comes out clean, about 25 minutes
• Transfer tins to wire racks to cool 10 minutes; turn out cupcakes onto racks and let cool completely
• Cupcakes can be stored up to 3 days at room temperature, or frozen up to 2 months, in airtight containers
• To finish, place cupcakes on a wire rack set over a baking sheet; spoon icing over cupcakes and let set
• Cupcakes are best eaten the day they are glazed; keep at room temperature until ready to serve

Brown Butter Icing

• Melt butter in a small saucepan over medium heat, swirling pan occasionally, until nut-brown in color, about 10 minutes
• Remove from heat, and pour butter into a bowl, leaving any burned sediment behind
• Add confectioners' sugar, vanilla, and 2 tablespoons milk to brown butter; stir until smooth
• If necessary, add more milk (up to 2 tablespoons) a little at a time, just until icing is spreadable Use immediately