Preheat oven to 350 degrees F. Line cupcake pan with 12 liners, set aside.
Whisk the flour, baking powder, baking soda, and salt in a bowl and set aside.
In a microwave-safe bowl, melt your butter. Remove from microwave and whisk in sugar until completely combined with no lumps.
Add to a large bowl and combine with egg, sour cream, milk, and vanilla until completely combined.
Gently add in the flour and whisk until combined, careful not to over mix.
Using a cookie scoop, add batter to cupcake liners evenly across all 12. Bake in the oven for 18-20 minutes, rotating the pan about halfway through cooking.
Remove from oven and let cool completely. When completely cool, frost the cupcake with white chocolate icing and then top with ghost candy. Enjoy!