Kentucky Derby Pie Cupcakes

INGREDIENTS

• :
• 1½ cups cake flour
• ½ teaspoon baking powder
• ¼ teaspoon baking soda
• ½ teaspoon kosher salt
• ¾ cup chopped walnuts
• ½ cup semisweet mini chocolate chips
• ½ cup buttermilk, at room temperature
• 2 tablespoons bourbon
• ½ cup unsalted butter, at room temperature
• ¾ cup granulated sugar
• ¼ cup light brown sugar
• 2 eggs, at room temperature
• 1 cup unsalted butter, at room temperature
• 2½ cups powdered sugar
• Pinch salt
• 1 tablespoon vanilla extract
• 1 tablespoon bourbon
• 2 tablespoons unsalted butter
• ¼ cup granulated sugar
• 1 tablespoon + 1 teaspoon bourbon