Preheat Oven & Prepare Pan: Preheat your oven to 350°F (175°C). Line a 12-cup muffin tin with cupcake liners.
Combine Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
Cream Butter and Sugar: In a large bowl, cream together the softened butter and granulated sugar until light and fluffy. This will take about 3-5 minutes with an electric mixer.
Add Eggs and Vanilla: Beat in the eggs one at a time, then stir in the vanilla extract.
Alternate Wet and Dry Ingredients: Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk. Begin and end with the dry ingredients. Mix until just combined. Do not overmix.
Fill Cupcake Liners: Fill each cupcake liner about 2/3 full.
Bake: Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Cool: Let the cupcakes cool in the muffin tin for a few minutes before transferring them to a wire rack to cool completely.
Instructions (Glow-in-the-Dark Decoration – Choose ONE or combine):
Option 1: Tonic Water Frosting:
