For the cake: 2 1/2 cups all-purpose flour 2 tsp baking powder 1/2 tsp salt 1 cup unsalted butter, softened 2 cups granulated sugar 4 large eggs Zest of 2 lemons 1/4 cup fresh lemon juice 1 cup buttermilk
For the frosting: 1 cup unsalted butter, softened 4 cups powdered sugar 2 tbsp fresh lemon juice 1 tsp vanilla extract