Preheat your oven to 350°F (175°C) and line the muffin tin with cupcake liners.
In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, and salt until well combined.
In another bowl, cream the softened butter with an electric mixer until light and fluffy. Add the eggs, buttermilk, lemon zest, lemon juice, and vanilla extract, and mix until combined.
Gradually add the dry ingredient mixture to the wet ingredients, mixing until just incorporated. Do not over mix the batter.
Evenly distribute the cupcake batter into the prepared muffin tin, filling each liner about two-thirds full.
Bake in the preheated oven for 15-18 minutes, or until a toothpick inserted into the center of a cupcake comes out clean. Remove from the oven and let them cool in the tin for about 5 minutes before transferring to a cooling rack.
While the cupcakes cool, prepare the raspberry buttercream. In a mixing bowl, beat the softened butter until creamy. Gradually add the powdered sugar, mixing until smooth.
Add the fresh raspberries, heavy cream, vanilla extract, and a pinch of salt to the butter mixture. Beat until well combined and smooth.
Once the cupcakes are completely cool, frost them with the raspberry buttercream using a piping bag or a spatula.
Enjoy your delicious lemon cupcakes with raspberry buttercream frosting!