Preheat your oven to 350°F and line 14 cupcake tins with liners.
In a small bowl, stir the cocoa powder and espresso powder together. Pour the hot water or coffee over and stir until powders are dissolved. Set this aside for now.
In an electric mixer, beat the butter and sugars together on medium-high speed for 2 minutes. Scrape down the sides of the bowl.
Add the eggs, one at a time, mixing until each is fully combined. Then drizzle in the oil and continue to beat on medium-high speed for 2-3 minutes, or until the mixture is very creamy.
Warm the buttermilk for 12 seconds in the microwave to bring it to room temperature, then stir in the cocoa mixture and vanilla. While running your mixer on low, begin drizzling this mixture into the bowl, beating until it is fully combined.
Combine the flour, baking powder, and salt, and then gently fold it into the wet ingredients until just combined. Lastly, stir in the caramel sauce.
Divide the batter between the cupcake liners, filling to ¾ full. Bake for 18-20 minutes, or until cupcakes are set. Let them cool completely before frosting. C