Preheat your oven to 350°F (175°C). This ensures that your cupcakes bake evenly.
Line a muffin pan with cupcake liners. This will make it easier to remove the cupcakes after baking and keep them moist.
In a large mixing bowl, combine the chocolate cake mix, all-purpose flour, granulated sugar, and salt. Whisk together until everything is well blended.
In another bowl, whisk together the water, vegetable oil, vanilla extract, sour cream, and eggs. Make sure everything is well combined.
Pour the wet mixture into the dry ingredients. Using an electric mixer, beat on medium speed for 2 minutes until the batter is smooth and well incorporated.
Gently fold in the dark chocolate chips until evenly distributed throughout the batter.
Scoop the batter into the prepared muffin pan, filling each liner about 2/3 full. This allows room for the cupcakes to rise.
Bake in the preheated oven for 18-22 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove the pan from the oven and let the cupcakes cool in the pan for 5 minutes. Then transfer them to a wire rack to cool completely.
In a large mixing bowl, beat the salted butter and cream cheese together until creamy and smooth. Gradually add the sifted powdered sugar, mixing on low speed until combined. Add the milk and vanilla extract, then beat on high for about 2-3 minutes until fluffy.
Once the cupcakes have cooled completely, use a spatula or piping bag to frost each cupcake with the cream cheese frosting. Finish with a sprinkle of dark chocolate chips on top for that extra touch!
