01 - Preheat oven to 350°F. Grease and line three 8-inch round cake pans with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, and salt.
03 - In a large bowl, beat butter and sugar with an electric mixer until light and fluffy, approximately 3 minutes.
04 - Add eggs one at a time, mixing well after each addition.
05 - In a separate bowl, combine milk, pink lemonade concentrate, lemon juice, and lemon zest.
06 - With mixer on low speed, add flour mixture to butter mixture in three parts, alternating with lemonade mixture, beginning and ending with dry ingredients. Mix until just combined.
07 - If desired, add a few drops of pink food coloring to achieve a pastel pink hue.
08 - Divide batter evenly among prepared pans and smooth tops with a spatula.
09 - Bake for 25 to 30 minutes, or until a toothpick inserted in the center comes out clean.
10 - Allow cakes to cool in pans for 10 minutes, then turn out onto wire racks to cool completely.
11 - Beat softened butter until creamy. Gradually add powdered sugar and mix until smooth. Add pink lemonade concentrate, lemon juice, and salt. Beat until fluffy, adding heavy cream as needed for desired consistency. Tint with pink food coloring if desired.
12 - Place one cooled cake layer on serving plate. Spread with buttercream. Repeat with remaining layers. Frost sides and top with remaining buttercream.
13 - Decorate with lemon slices, sprinkles, or edible flowers if desired.