Line a cupcake pan and preheat oven to 350°F (175°C).
Whisk flour, baking soda, baking powder, salt, and milk powder.
In another bowl, beat butter, oil, and sugar until fluffy.
Add eggs and vanilla, mixing well.
Gradually add dry ingredients, then mix in sour cream and milk until smooth.
Fill liners halfway and bake for 13–15 minutes until lightly golden. Cool completely.