01 - Preheat oven to 350°F. Grease and line three 8-inch round cake pans with parchment paper.
02 - In a bowl, whisk together flour, baking powder, baking soda, and salt until evenly blended.
03 - In a large mixing bowl, beat butter, oil, and sugar until light and fluffy, about 3 minutes.
04 - Beat in eggs one at a time, mixing well after each addition. Add lemon zest and mix until incorporated.
05 - In a separate bowl, combine buttermilk, lemon juice, and pink lemonade concentrate.
06 - Alternately add the dry ingredients and the buttermilk mixture to the butter mixture, beginning and ending with the dry ingredients. Mix until just combined.
07 - Stir in pink food coloring, if using, until desired shade is achieved.
08 - Divide batter evenly among the prepared pans. Smooth tops. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
09 - Let cakes cool in pans for 10 minutes, then turn out onto 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 a serving plate. Spread with frosting. Repeat with remaining layers. Frost sides and top of cake. Decorate with lemon slices, edible flowers, or sprinkles if desired. Chill 30 minutes before slicing for cleaner cuts.