Prepare and bake cake mix according to package directions to make 22 cupcakes. Allow to cool completely.
In a microwave-safe bowl, add unwrapped caramels and heavy cream. Microwave in 30-second increments, stirring each time, until caramels have melted. Stir in salt, mixing until smooth.
In a bowl, combine the vanilla frosting and ¼ cup of the salted caramel sauce with an electric hand mixer. Set aside.
Use a wide spoon handle to make an indent in the top of each cupcake. Add 1 teaspoon of the salted caramel sauce in each hole*.
Spread the frosting over each cupcake. Drizzle the remaining salted caramel sauce over the icing. Sprinkle with flaky salt if desired.
Notes
*If the caramel sauce firms up at any point and is hard to work with, microwave it for 15-25 seconds or until soft.
Instead of cake mix, use your favorite cupcake recipe or purchase premade, undecorated cupcakes.
Leftovers will keep in an airtight container at room temperature for 3 days.