Start by preheating your oven to 350°F (175°C) and lining a 12-cup muffin tin with cupcake liners. In a medium bowl, whisk together the flour, baking powder, and salt. Set this dry mixture aside.

In a separate large bowl, cream the softened butter and granulated sugar until light and fluffy. This should take about 2–3 minutes with an electric mixer. Add the eggs one at a time, beating well after each addition. Then mix in the vanilla extract, lemon zest, and lemon juice.

With the mixer on low speed, alternate adding the dry ingredients and the milk, starting and ending with the flour mixture. Mix just until combined—overmixing can lead to dense cupcakes. Gently fold in the raspberries that have been lightly tossed in flour to prevent sinking.

Divide the batter evenly between the prepared cupcake liners, filling each about ¾ full. Bake for 18–22 minutes, or until a toothpick inserted in the center comes out clean. Allow the cupcakes to cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely before frosting.

To make the frosting, beat the softened butter and cream cheese (if using) until smooth and creamy. Add powdered sugar gradually, then mix in lemon juice and zest. Adjust the consistency as needed by adding more powdered sugar or a splash of milk. Once the cupcakes are cool, frost using a piping bag or spread with a knife. Garnish with fresh raspberries or lemon slices for an extra special touch.