1) Preheat the oven to 350°F. Line two standard 12-cup muffin pans with greased cupcake papers.
2) To make the cupcakes: Whisk together the dry ingredients; set aside.
3) Whisk together the eggs, milk, and vanilla, and stir into the dry ingredients.
4) Fold in the vinegar, butter, and chocolate chips.
5) Divide the batter among the muffin cups, filling them quite full.
6) Bake the cupcakes for 23 to 25 minutes, until a toothpick inserted into the center comes out clean.
7) Remove the cupcakes from the oven, and turn them out of the pan onto a rack to cool.
8) Once cool, remove a teaspoon-sized portion from the top of each cake; a cupcake corer works well here.
9) To make the frosting: Beat together the butter, meringue powder, and peppermint.
10) Add the confectioners' sugar and milk, beating until light and fluffy.
11) Pipe or spoon frosting into the center of each cupcake, and garnish with a fresh mint leaf, if desired.
Yield: 24 cupcakes.