Preheat the oven to 350°F. Line a 12-cup muffin pan with cupcake liners.
Using mixer, beat the butter and sugar together on medium-high speed in a large bowl until creamed, about 2 minutes. Scrape down the sides and bottom as needed.
Add eggs and vanilla extract, then beat on medium-high speed until just combined (about 1 minute). Scrape down the sides and bottom of the bowl as needed. Set aside.
Whisk the flour, baking powder, and salt together in a medium bowl. Pour the dry ingredients into the wet ingredients. Start the mixer on low speed, then slowly add the milk, lemon juice, and lemon zest. Be careful not over-mix.
Spoon batter evenly into 12 cupcake liners, filling them about 2/3 full and bake for about 18-22 minutes. Insert a toothpick into the middle and it will come out clean when they’re done. Allow to cool completely before frosting.
Frost cooled cupcakes with vanilla buttercream. Top with lemon zest right before serving.