Preheat oven to 350°F. Line a muffin tin with liners; set aside.
Using an electric mixer, cream butter and sugar at medium-high speed until fluffy, about 3 minutes. Add eggs one at a time, beating after each. Mix in vanilla, baking powder and salt at low speed. Mix in half of flour; add milk and remaining flour; mix at low speed until smooth.
Spoon batter into prepared cups. Bake until a cake tester comes out clean, 20 minutes. Let pan cool.
Frost with buttercream and decorate as desired.
This is very simple and easy to make and very kid friendly, will eventually try with flavor variations..