01 - Preheat oven to 350°F. Grease and line three 8-inch round cake pans with parchment paper.
02 - Whisk together flour, baking powder, baking soda, and salt in a bowl.
03 - Beat butter, oil, and sugar in a large mixing bowl until light and fluffy, approximately 3 minutes.
04 - Beat in eggs one at a time, mixing thoroughly after each addition. Add lemon zest and combine.
05 - Combine buttermilk, lemon juice, and pink lemonade concentrate in a separate bowl.
06 - Alternately add dry ingredients and buttermilk mixture to butter mixture, beginning and ending with dry ingredients. Mix until just incorporated.
07 - Fold in pink food coloring if using, stirring until desired shade is achieved.
08 - Divide batter evenly among prepared pans. Smooth tops and bake for 25-30 minutes until a toothpick inserted in center emerges clean.
09 - Let cakes cool in pans for 10 minutes, then transfer to wire racks to cool completely.
10 - Beat butter until creamy. Gradually add powdered sugar, beating well after each addition.
11 - Add pink lemonade concentrate, lemon juice, food coloring, and salt. Beat until light and fluffy.
12 - Place one cake layer on serving plate. Spread with frosting. Repeat with remaining layers. Frost sides and top of cake.
13 - Decorate with lemon slices, edible flowers, or sprinkles if desired. Refrigerate for 30 minutes before slicing for cleaner cuts.