Put the flour, sugar, baking powder, salt, and butter in a freestanding electric mixer with a paddle attachment* and beat on slow speed until you get a sandy consistency and everything is combined.
Gradually pour in half the milk and beat until the milk is just incorporated.
Whisk the egg, vanilla, and remaining milk together in a separate bowl for a few seconds, then pour into the flour mixture and continue beating until just incorporated. Continue mixing for a couple more minutes until the batter is smooth, but do not overmix.
Spoon the batter into cupcake cases until two-thirds full and bake for 20-25 minutes, or until light golden and the cake bounces back when touched.
When done (you can test this by inserting a toothpick in the center; if it comes out clean when you pull it out, the cupcakes are ready to go), let the cupcakes cool slightly in the pan before letting cool on a wire rack.
From The Hummingbird Bakery Cookbook
The cookbook claims that the recipe will yield 12 cupcakes; I’ve made these cupcakes a bunch of times and it has only ever yielded 10.