Step 1: Prepare the Oven
- Preheat oven to 350°F (175°C).
- Line a 12-cup muffin pan with cupcake liners.
Step 2: Mix the Dry Ingredients
In a medium bowl whisk together:
- Cake flour
- Sugar
- Baking powder
- Salt
Set aside.
Step 3: Mix the Wet Ingredients
In another bowl whisk together:
- Milk
- Sour cream
- Vanilla extract
- Vegetable oil
Set aside.
Step 4: Cream the Butter
Using an electric mixer, beat the softened butter for about 2–3 minutes until smooth and creamy.
Step 5: Add the Eggs
Beat in:
- 1 whole egg
- Then the 2 egg whites
Mix until light and fluffy.
Step 6: Combine Everything
Add the dry ingredients in three additions, alternating with the milk mixture.
Mix on low speed:
- ⅓ dry ingredients
- Half the milk mixture
- ⅓ dry ingredients
- Remaining milk mixture
- Remaining dry ingredients
Mix only until combined.
Do not overmix.
Step 7: Fill the Cupcake Liners
Fill each liner about ⅔ full.
Using an ice cream scoop helps keep every cupcake the same size.
Step 8: Bake
Bake for 20–24 minutes, or until:
- The tops spring back when lightly touched.
- A toothpick inserted into the center comes out clean.
Step 9: Cool
Allow cupcakes to cool:
- 5 minutes in the pan
- Then transfer to a wire rack until completely cool.
Never frost warm cupcakes.