01 -
Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
02 -
Whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt.
03 -
Add the milk, vegetable oil, egg, and vanilla extract. Mix until well combined, then carefully stir in boiling water until smooth.
04 -
Divide the batter among the cupcake liners and bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean. Let the cupcakes cool completely.
05 -
For the caramel filling, melt the sugar in a medium saucepan over medium heat, stirring constantly until golden brown. Add the butter, then heavy cream, and sea salt, and stir until smooth. Let the caramel cool slightly.
06 -
Cut a small hole in the top of each cooled cupcake and fill it with a teaspoon of caramel.
07 -
To make the frosting, beat the softened butter until creamy. Gradually add powdered sugar, then mix in the salted caramel sauce, heavy cream, and vanilla extract. Beat until light and fluffy.
08 -
Pipe or spread the frosting onto each cupcake. Drizzle with additional caramel sauce and sprinkle with sea salt for extra flavor.