Preheat Your Oven: Set your oven to 350°F and line the muffin tin with 16 cupcake liners.
Mix the Dry Ingredients: Combine sugar, flour, baking powder, baking soda, and salt in a large bowl.
Incorporate the Butter: Add softened butter to the dry ingredients and beat on low until it resembles a sandy texture.
Add the Wet Ingredients: In another bowl, whisk eggs, sour cream, oil, and vanilla. Slowly add this to the dry mixture, stirring until smooth.
Finish with Milk: Pour in the milk, mixing on medium speed until creamy and lump-free.