In a medium saucepan over medium-heat, add the sugar. Once the sugar starts to melt and clump together, continuously whisk it until completely melted. Allow the melted sugar to sit until it starts to turn amber in color (about 10-15 seconds). Then remove it from the heat.
Add the cubed butter and constantly whisk it until melted. Then add the heavy whipping cream, whisking constantly until incorporated. Then whisk in the salt and vanilla extract.
Pour the hot caramel into a glass bowl, jar, or container and cool completely before using. The caramel will thicken up as it cools down.
Chocolate Cupcakes
Preheat the oven to 350 degrees and line a 12-count muffin pan with cupcake liners. Set aside.
In a medium-sized bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
In a large bowl, whisk together the milk, oil, warm water, egg, and vanilla extract. Add the flour mixture to the wet ingredients and whisk just until combined (the batter will be thin).
Fill the cupcake liners a little more than½ way full (exactly 3 tablespoons) and bake for 16-20 minutes, or until a toothpick inserted into the middle of the cupcake comes out clean. Allow them to cool in the pan for 10 minutes and then transfer them over to a wire rack to finish cooling.
Salted Caramel Frosting
In an electric stand mixer using the paddle attachment, beat the butter on high speed until creamy (1-2 minutes). Add the powdered sugar, heavy whipping cream, and vanilla extract and mix on low speed until combined (about 30 seconds). Then pour in a ¼ cup of the cooled salted caramel sauce. Increase the speed to high and mix until smooth and creamy (1-2 minutes).
Assemble
In a small heat-safe bowl, melt the chocolate chips in 20-second intervals until melted. Set aside.
Once the cupcakes have cooled, use a piping tip (or a small sharp knife) to carefully cut out the centers. Be careful not to go through the bottom of the cupcake. Fill each cupcake with the salted caramel sauce.
Frost the cupcakes. I placed the frosting in a piping bag and used the Wilton 6B piping tip. Drizzle on the melted chocolate over the tops of each cupcake.
Keep any leftover cupcakes in an airtight container at room temperature for 2 days or in the refrigerator for up to 5 days.
Notes
Caramel: Make the caramel sauce first so it has plenty of time to cool before you need it.Cupcake Pan: Prep a 12-count muffin pans with cupcake liners. Measuring Flour: To help ensure you don’t add extra flour, follow these three simple steps: 1) Fluff up the flour using a fork. 2) Spoon the flour into your measuring cup. 3) Scrape a knife across the top of the measuring cup to level out the flour.
Cupcake Batter: Evenly divide the batter amongst the cupcake liners, filling them a little over ½ way full (exactly 3 tablespoons). If you fill them any more than that the cupcakes will have large muffin tops and will risk sinking once cooled.
Assembling: Use a piping tip to carefully core out the centers of each cupcake. Then spoon in the caramel into each hole.