Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
In a large 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. Then stir in the vanilla extract and lemon zest.
In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the butter mixture, alternating with the milk and pink lemonade concentrate. Mix until just combined.
Divide the batter evenly between the prepared cake pans. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.
While the cakes are cooling, prepare the frosting by mixing the powdered sugar, lemon juice, and pink lemonade concentrate in a bowl until smooth.
Once the cakes are completely cool, spread a layer of frosting on top of one cake layer, then place the second layer on top and frost the top and sides of the cake.
Garnish with fresh raspberries or lemon slices if desired.