1. Preheat the oven to 350°F and line a 12-cup muffin pan with cupcake liners.

2. In a medium bowl, whisk together the flour, cocoa powder, baking soda, and salt.

3. In a large bowl, whisk together the sugar, vegetable oil, and eggs until smooth.

4. Add the buttermilk, vanilla extract, green food coloring, and vinegar, then whisk until evenly combined.

5. Add the dry ingredients to the wet ingredients and stir just until no dry streaks remain.

6. Divide the batter evenly among the cupcake liners, filling each about two-thirds full.

7. Bake for 18 to 22 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.

8. Cool the cupcakes in the pan for 5 minutes, then transfer them to a wire rack to cool completely.

9. In a separate bowl, beat the cream cheese and butter until smooth and creamy.

10. Add the powdered sugar gradually, then mix in the vanilla extract until the frosting is fluffy.

11. Pipe or spread the frosting onto the cooled cupcakes and serve.