1. Preheat your oven to 350°F (175°C) and line a 12-cup muffin pan with cupcake liners. Set aside.

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

3. In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy, about 2 to 3 minutes. Scrape down the sides as needed.

4. Add the egg and mix until fully blended, then stir in the vanilla extract.

5. In a small bowl, combine the buttermilk, vinegar, and pink food coloring. Mix well so the color is evenly distributed.

6. Add the dry ingredients to the butter mixture in two additions, alternating with the buttermilk mixture. Begin and end with the dry ingredients, mixing gently just until combined.

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

8. Bake for 18 to 22 minutes, or until a toothpick inserted into the center comes out clean or with a few soft crumbs.

9. Remove the cupcakes from the oven and let them cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.

10. Beat the softened butter on medium speed until smooth and creamy, about 2 minutes.

11. Gradually add the powdered sugar, one cup at a time, mixing on low speed.

12. Add the vanilla extract, salt, and 2 tablespoons of cream or milk. Beat on medium-high speed until light and fluffy, about 3 minutes.

13. Adjust the consistency by adding more cream or powdered sugar as needed.

14. Once the cupcakes are fully cooled, frost them using a piping bag or spatula as desired.