Buttermilk (Best Option)
1 cup buttermilk per 1 cup whole milkButtermilk works well because its acidity reacts with baking soda to create carbon dioxide, which helps cupcakes rise and develop a tender crumb. It also has a similar fat and moisture content to whole milk, preserving texture and richness.
For best results, reduce baking powder slightly or add 1/4 teaspoon baking soda per cup of buttermilk to balance leavening. Watch for slight tangy flavor, which usually complements cupcake flavors.
Compared to whole milk, buttermilk produces a moister, slightly tangier cupcake with a tender crumb and good rise, often enhancing flavor complexity.