Preheat your oven to 350°F (175°C). Line a 12-cup cupcake pan with paper liners and set aside. This will ensure your cupcakes bake evenly and are easy to remove.

In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. In a separate small bowl, combine the white sugar with the finely grated zest from 2 large lemons. Rub the zest into the sugar with your fingers until fragrant, which helps release the lemon oils and infuse more flavor.

In a stand mixer, beat the soft unsalted butter together with the lemon sugar mixture until light and fluffy, and visibly lighter in color—this takes about 8 minutes. Scrape down the sides of the bowl as needed. Add eggs, one at a time, beating well after each addition, then blend in the vanilla extract. With the mixer on low speed, add the flour mixture and whole milk alternately, starting and finishing with the flour. Mix just until combined, taking care not to overmix. Finally, mix in the freshly squeezed lemon juice. I always make sure to scrape the bowl one last time to ensure the batter is evenly mixed.

Divide the batter evenly among the prepared cupcake liners, filling each about two-thirds full. Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted in the center comes out clean. Once baked, transfer the pan to a wire rack and allow the cupcakes to cool completely before filling and frosting. I like to check them at the 18-minute mark to prevent overbaking.

While the cupcakes cool, make the frosting. In a stand mixer, beat the room-temperature unsalted butter until creamy and smooth. With the mixer on low, gradually add the confectioners' sugar, one cup at a time, until all is incorporated. Add the whole milk, vanilla extract, and finely grated zest of 1 lemon, then beat on high until the frosting is smooth and fluffy. For an extra zesty touch, I sometimes add a tiny extra squeeze of lemon juice at this stage.

Once the cupcakes have cooled, use a knife to cut a small hole in the center of each cupcake. Carefully remove the center piece and set it aside. Fill each hole with about 1 teaspoon of prepared lemon curd. Replace the top of the piece you removed to cover the lemon curd, or leave the curd exposed if you prefer. Fill a pastry bag with the prepared frosting (from Step 5) and frost each cupcake generously. Decorate with yellow sprinkles if desired and serve fresh! I find that adding the lemon curd makes the cupcakes extra moist and tangy.