In large bowl, whisk together flour, sugar, baking powder and salt.
Using electric mixer on low speed, mix in butter, milk, eggs and vanilla; beat on high speed until smooth, about 2 minutes.
Spoon into 12 cupcake or muffin cups or papers, filling about three-quarters full.
Bake in centre of 375°F (190°C) oven until cake tester inserted in centre comes out clean, about 18 minutes.
Transfer to rack; let cool completely.
In large bowl, beat butter until light and fluffy.
Alternately beat in sugar and cream, making 2 additions of sugar.
Beat in vanilla.
