Preheat oven to 350°F (175°C) and line a muffin tin with cupcake liners.
Prepare the cupcakes: In a bowl, whisk flour, baking powder, and salt. In another bowl, beat butter and sugar until light and fluffy. Add eggs one at a time, then mix in vanilla. Gradually add dry ingredients, alternating with milk.
Divide the batter evenly into the liners, filling each about ⅔ full. Bake for 18-20 minutes, or until a toothpick inserted comes out clean. Let cool completely.
Fill the cupcakes: Using a small knife or cupcake corer, remove a small center portion from each cupcake. Spoon in about 1 teaspoon of salted caramel sauce into each hole.
Make the frosting: Beat cream cheese and butter until smooth. Add powdered sugar and vanilla, beating until fluffy.
Pipe or spread the frosting onto each cupcake, then drizzle with extra caramel sauce and a sprinkle of sea salt.