Preheat oven to 350°F (180°C). Grease and flour pan.
Sift together cake flour, baking powder, baking soda, and salt. Whisk to combine.
Combine buttermilk and lemon juice, whisking together.
Beat butter, sugar, and lemon zest until light and fluffy.
Beat in vanilla extract, then add eggs one at a time, beating well after each.
Add flour mixture and buttermilk mixture alternately, avoiding overmixing.
Toss blueberries with flour, then fold into batter.
Pour batter into pan(s). Bake 30-35 minutes, until done.
Let the cakes cool in the pans.
Beat butter until soft, then add cream cheese and mix until smooth. Add lemon juice, then gradually beat in powdered sugar. Adjust frosting thickness with whipping cream.
Frost the cooled cake and garnish optionally with blueberries and lemon slices.
Slice with a thin, sharp knife to serve.
Notes
For best results, use room temperature ingredients.