For the Caramel Cupcakes

1. Preheat your oven to 350 degrees Fahrenheit and line a 12-count muffin pan with liners.
2. In a medium bowl, whisk all purpose flour, baking powder, baking soda, and salt together until combined. Set aside.
3. In a large bowl, whisk melted butter, dark brown sugar, a room temperature egg, vanilla extract, and room temperature buttermilk together until smooth.
4. Add the medium bowl of dry ingredients to the bowl of wet ingredients. Mix only until you see the dry ingredients disappear, as mixing past once the dry pieces have incorporated could lead to dry, dense cupcakes.
5. Transfer the batter between the liners, adding about 1/4 cup of batter to each liner. Bake the cupcakes for 17-21 minutes or until the tops are light golden brown, domed, and a toothpick inserted into the center comes out with moist crumbs. Allow the cupcakes to cool before decorating.

For the Fudge Buttercream

1. In a large bowl with a hand mixer or in the bowl of a stand mixer fitted with a paddle attachment, beat room temperature butter until smooth. This should be about 2 minutes of mixing.
2. Slowly, add powdered sugar and cocoa powder into the butter. Beat on low speed, adding the powdered sugar and cocoa powder in small increments to avoid spilling.
3. Pour heavy cream into the frosting and beat on high speed for at least 3 minutes. This creates a light, velvety frosting. Scrape down the sides and the bottom of the bowl with a rubber spatula to ensure the frosting is even throughout.
4. If desired, transfer the frosting to a piping bag fitted with your desired tip or a zippable plastic bag with the corner snipped off for greater control when frosting.

For Decorating

1. Use a knife to cut out a portion of the center of each cupcake or use a spoon to dig and create a well.
2. Add about 1/2 tablespoon-1 tablespoon of caramel sauce to the center of each cupcake.
3. Frost each cupcake as desired.
4. Immediately, top the cupcakes with a piece of shortbread and drizzle additional caramel on top.
5. Store the cupcakes tightly covered or in an airtight container at room temperature for up to 3 days, in the fridge for up to 4 days, or in the freezer for up to 3 months.