High Altitude Adjustments: Above 4000 feet, reduce the baking powder to 1 teaspoon and the sugar to 1¾ cups. Above 6000 feet, I would reduce the baking powder to ½ teaspoon. See post above for troubleshooting.
Egg-Free & Vegan Option: Omit the eggs. Increase the milk beverage to a scant 1¾ cups, the flour to 3 cups, the baking powder to 2 teaspoons, and the baking soda to 1 teaspoon (only use ½ teaspoon at high altitude). Add ½ teaspoon ground turmeric to the dry ingredients to achieve a notable yellow hue. Bake as directed above.
Half Batch (12 cupcakes): Simply cut all ingredients in half. Half of ¾ cup is 6 tablespoons. The instructions stay the same, except you will need less pans and cupcake liners.
Quarter Batch (6 cupcakes): Use ⅔ cup all-purpose flour, ⅜ teaspoon baking powder, ⅛ teaspoon baking soda, ⅛ teaspoon salt, 1 egg, 3 tablespoons butter alternative, ½ cup sugar, ¾ teaspoon vinegar, ½ teaspoon vanilla extract, and ¼ cup + 2 teaspoons milk alternative. You will only need 6 lined muffin cups.