Preheat oven to 375°F or 190°C.
Line muffin pans with paper baking cups.
Cream the butter and sugar until smooth and creamy.
Add the eggs, beating in one at a time until well combined.
Mix in the milk, lemon zest and vanilla.
Sift flour, salt and baking powder together in a bowl, before gradually adding to the liquid mixture.
Beat at low speed until smooth and then spoon into the muffin cups.
Bake for 20 -25 minutes or until toothpick inserted in center comes out clean.
Makes 10 cupcakes.