2 sticks (1/2 pound) unsalted butter, at room temperature
3/4 cup water
1 cup milk
1 teaspoon balsamic vinegar
2 large eggs
1 teaspoon vanilla extract
2-1/4 cups all-purpose flour
2 teaspoons baking soda
1 teaspoon baking powder
1 teaspoon table salt
1 batch Vanilla Frosting (see accompanying recipe)
Preheat oven to 350°. Line 16 standard-size muffin cups with paper liners. Set aside.
In a large double boiler over simmering water, stir together sugar, chocolate, butter, and water; whisk well to combine. Let cool to room temperature. Stir in milk, vinegar, eggs, and vanilla, and set aside.
In a separate bowl, whisk together flour, baking soda, baking powder, and salt. Fold into chocolate mixture.
Divide batter among muffin cups, filling to just below rim. Bake 15—20 minutes (tops will spring back when lightly touched). Let cool completely, and top with Vanilla Frosting.