01 - Preheat oven to 350°F. Grease and flour two 8-inch round cake pans; line bottoms with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, baking soda, and salt until evenly distributed.
03 - In a large mixing bowl, beat softened butter and granulated sugar until light and fluffy, approximately 3 minutes. Add eggs one at a time, beating well after each addition. Blend in lemon zest, lemon juice, and vanilla extract.
04 - Alternately add the flour mixture and buttermilk to the wet ingredients, beginning and ending with the flour. Stir gently until just combined.
05 - Gently fold diced strawberries into the batter using a spatula, taking care not to overmix.
06 - Divide batter evenly between the two prepared pans. Bake for 25–30 minutes, or until a toothpick inserted into the center comes out clean.
07 - Let cakes cool in pans for 10 minutes, then invert onto wire racks to cool completely before frosting.
08 - Beat butter until creamy. Gradually add sifted powdered sugar, then mix in lemon juice and strawberry puree. Beat until smooth and fluffy. Add a pinch of salt to taste.
09 - Place one cake layer on a serving plate and spread one-third of the frosting evenly on top. Set the second layer on top and frost the sides and top of the cake. Garnish with lemon zest and fresh strawberry slices if desired.