Preheat the oven: Preheat oven to 356ºF (180ºC). Line a muffin/cupcake baking pan with regular sized paper cups. This recipe makes 6 regular sized cupcakes.
Prepare the dry ingredients: In a medium size mixing bowl, add flour, baking powder, and salt. Whisk until well combined.
Rub lemon zest: Add the lemon zest to the flour mixture. Using your hands, rub the zest into the flour to release the natural oils of the lemon. Set aside.
Beat the butter: In a separate large mixing bowl, using either electric hand beaters or a stand mixer with the paddle attached, add softened butter to the bowl. Beat butter for a few seconds to break it up and it begins to turn creamy. This makes it easier on your beater when the sugar is added.
Cream the butter and sugar: Add sugar and lemon zest and beat with the butter for 1 minute until pale and creamy. Scrape down the sides.
Add the egg: Add egg and beat for 15 seconds.
Incorporate the wet ingredients: Pour in milk, oil, lemon juice and vanilla. Beat for 20 seconds until well combined. Scrape down the sides again.
Combine with dry ingredients: Add the dry flour mixture and beat until incorporated. Ensure not to over-beat, just until the flour has combined then turn off the beater. If some excess flour is still visible around the sides of the bowl, gently fold it in with a spatula.
Fill the cupcake liners: Spoon and evenly distribute the batter into the paper cups, filling each 3/4 of the way full. The batter will make 6 even cupcakes.
Bake the cupcakes: Bake for 18-20 minutes or until a toothpick inserted into the middle comes out clean and they’re lightly golden.
Cool the cupcakes: Remove from oven and allow cupcakes to cool in pan for 5 minutes. Carefully transfer to a wire rack to cool completely.