Preheat your oven to 375°F (190°C) and line a 12-cup cupcake with liners.
In a large mixing bowl, use an electric mixer to beat the butter and sugar together until light and fluffy (for about 2 to 3 minutes).
Add the eggs one at a time, beating well after each addition to ensure a smooth mixture.
In a small bowl, stir together the wet ingredients: vanilla extract, lemon juice, and salt.
In another bowl, whisk together the dry ingredients: flour and baking powder.
With the mixer on low, slowly add the dry ingredients to the butter mixture in batches, alternating with half the milk and half of the lemon juice mixture. Scrape down the sides of the bowl between each addition. Repeat until everything is fully combined.
Divide the batter evenly among the cupcake liners (3/4 full). Bake for 17–20 minutes, or until a toothpick inserted in the center comes out clean.
Remove the cupcakes from the oven and let them cool in the pan for 5 minutes. Then, transfer them to a wire rack to cool completely before frosting.