Preheat your oven to 350°F (175°C) and line a cupcake tin with paper liners.
In a large bowl, whisk together the flour, cocoa powder, sugar, baking powder, baking soda, and salt.
Add the vegetable oil, milk, eggs, and vanilla extract. Mix until smooth.
Divide the batter evenly among the cupcake liners, filling each about ⅔ full.
Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean. Let cool completely.
For the frosting, beat the softened butter until creamy. Gradually add the powdered sugar, then mix in the Nutella and heavy cream until smooth and fluffy.
Pipe the Nutella frosting onto the cooled cupcakes and enjoy!