Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
Add the eggs one at a time, mixing well after each addition.
Stir in the milk, lemon zest, lemon juice, and vanilla extract until combined.
In another bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, mixing just until combined.
Divide the batter evenly among the cupcake liners, filling each about ⅔ full.
Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted in the center comes out clean.
Allow the cupcakes to cool in the tin for 5 minutes, then transfer them to a cooling rack to cool completely.
While the cupcakes are cooling, prepare the raspberry buttercream frosting. In a mixing bowl, beat the softened butter until creamy.
Gradually add the powdered sugar, mixing on low speed until combined, then increase to medium speed.
Add the mashed raspberries, vanilla extract, and a pinch of salt. Mix until well combined.
If the frosting is too thick, add heavy cream a tablespoon at a time until desired consistency is reached.
Once the cupcakes are completely cool, frost them with the raspberry buttercream using a piping bag or a spatula.
Decorate as desired, and enjoy!