Preheat your oven to 168º C (335º F).

Prepare three 6"x 2" round cake pans or two 8"x 2" pans using cake release or your preferred pan coating.

Divide your buttermilk into two containers. In one, add the vegetable oil and set aside. In the other, add eggs, lemon extract, lemon juice, and lemon zest. Gently whisk to combine and set aside.

In the bowl of a stand mixer fitted with the paddle attachment, combine cake flour, sugar, baking powder, baking soda, and salt. Mix on low speed until well combined.

Add softened butter to the dry ingredients in small chunks while mixing on low speed. Keep going until the mixture resembles coarse sand.

Pour the buttermilk and oil mixture into the dry ingredients and mix on medium speed for 2 minutes to develop structure.

Scrape the sides of the bowl, gradually mixing in the remaining buttermilk mixture in three parts. Scrape halfway through for an even consistency.

Pour the batter into the prepared pans, filling them halfway. Gently tap each pan to level out the batter and remove air bubbles.

Toss blueberries in flour and scatter them on top of the batter. Do not mix them into the batter.

Bake in the oven, then gently tap the cakes on a countertop to release air and minimize shrinkage.

Cool the cakes on a rack until barely warm, then carefully invert and remove from pans.

Wrap the cakes in plastic wrap and chill them in the fridge or freezer for about 60 minutes to firm them up, making stacking easier when you’re ready to decorate.