01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners.
02 - In a medium bowl, whisk together flour, baking powder, and salt until well blended.
03 - In a large bowl, beat butter and sugar with an electric mixer on medium-high speed until light and fluffy, approximately 3 minutes.
04 - Add eggs one at a time, beating thoroughly after each addition. Mix in lemon zest and vanilla extract until fully incorporated.
05 - Pour in lemon juice and mix to combine. The batter may appear slightly curdled at this stage, which is normal.
06 - Add half of the flour mixture, followed by half of the milk, mixing on low speed. Repeat with remaining flour and milk, mixing just until combined. Do not overmix.
07 - Divide batter evenly among prepared cupcake liners, filling each about two-thirds full.
08 - Bake for 16-18 minutes, or until a toothpick inserted into the center comes out clean. Allow cupcakes to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.
09 - Once cooled, use a small knife or cupcake corer to remove a small core from the center of each cupcake. Fill each cavity with approximately 1 teaspoon of raspberry preserves.
10 - Beat butter until creamy. Add powdered sugar, lemon juice, lemon zest, and salt. Beat until smooth and fluffy, adding milk 1 tablespoon at a time as needed to achieve spreadable consistency.
11 - Pipe or spread buttercream onto filled cupcakes. Garnish with fresh raspberries or additional lemon zest if desired.