Preheat oven to 350°F. Line a cupcake pan with paper liners.
Whisk flour, baking powder, and salt in a bowl.
Beat softened butter and sugar until fluffy, about 2 minutes.
Beat in eggs one at a time, then mix in sour cream and pickle juice.
Stir in dry ingredients just until combined. Fold in chopped pickles.
Scoop ¼ cup batter into liners. Bake 20–25 minutes until a toothpick comes out clean. Cool completely.
Beat butter and cream cheese until smooth. Add powdered sugar, bourbon (or milk), and salt. Beat until fluffy.
Frost cooled cupcakes and top each with a pickle slice.