Soften the butter at room temperature and mix until smooth.

Gradually add sugar in three portions, mixing well after each addition.

Add eggs one at a time, or beat them together and add gradually while mixing. Add 1-2 drops of vanilla extract and mix.

Sift the dry ingredients twice and fold them into the wet mixture.

Transfer the batter into a piping bag and fill muffin cups lined with parchment paper to about 70% full.