I love using buttermilk for this recipe because it adds a nice tangy flavor to the cupcakes which goes great with the lemon flavor. Also, it makes the cupcakes very moist. It keeps the cupcakes from being too sweet but still makes them light and fluffy (like pancake consistency). If you don't have buttermilk, mix together 1 cup of whole milk with 1 tablespoon lemon juice or white vinegar. Let the mixture sit for 5-10 minutes and then you can use that mixture for the buttermilk in this recipe.