These double chocolate cupcakes are topped with a fluffy cinnamon buttercream and a super simple whiskey salted caramel sauce - no candy thermometer required! The cupcakes are almost brownie-like due to the melted dark chocolate and they're absolutely decadent!
Make the caramel. In a medium saucepan, bring the sugar, water and corn syrup to a boil over high heat. Cook until the sugar is dissolved, but DO NOT stir! Swirl the pan on the stove if you need to. Continue cooking, without stirring, until an amber caramel forms, about 6-7 minutes. Remove from the heat and carefully stir in the cream. Let cool for 1 minute, then stir in the whiskey.
Bring the mixture to a boil over medium-high heat and cook, stirring, for 1-2 minutes. Stir in the salt. Let the caramel sauce cool. (I made mine the night before but this isn't crucial.)
Next, make the cupcakes. Preheat oven to 350℉. Line a standard cupcake/muffin pan with cupcake liners. Add milk to a small bowl and stir in the apple cider vinegar. Set aside. Add chopped chocolate to a microwave safe bowl and microwave in 30-second increments, stirring in between, until melted. This should only take a minute or less. Let cool.
In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt. In a separate bowl, whisk together the sugar, brown sugar, and egg until smooth. Add the melted, cooled chocolate and whisk until smooth. Add the vanilla extract vegetable oil, and coffee, and whisk again until smooth. Finally add the milk mixture and whisk to combine.
Gradually add the dry ingredients to the wet, folding with a rubber spatula until just combined. Fill cupcake tins ¾ the way full and bake for 20-22 minutes or until centers are set and a toothpick comes out clean. Let cool completely.
Make the cinnamon buttercream. Add softened butter to a stand mixer fitted with the paddle attachment. Beat butter on medium-high speed for 2-3 minutes or until lighter in color and fluffy. Lower the speed and add the powdered sugar, gradually. Once powdered sugar is incorporated, raise speed to high and beat for an additional 2-3 minutes. Add the vanilla and cinnamon and beat again for a minute or so until fully combined. Pipe or spread the icing onto the cupcakes, then drizzle them with the cooled salted whiskey caramel. Serve!
*Whiskey salted caramel can be made ahead of time and stored at room temperature in a sealed container for up to 2 weeks! I wouldn't recommend refrigerating this before making the cupcakes, as it will not be as drizzle-able!