Preheat your oven to 335°F (170°C) and prepare three 7-inch round cake pans with cooking spray and parchment paper.

Cream together room temperature unsalted butter and granulated sugar for about 2 minutes until light and fluffy.

Gradually add the eggs, sour cream, and vegetable oil to the mixture, mixing until just combined.

In a separate bowl, whisk together cake flour, baking powder, and salt.

Combine buttermilk, lemon juice, and lemon zest in a measuring cup.

Alternately add the flour mixture and buttermilk mixture to the batter, mixing on low speed until just incorporated.

Gently fold in the fresh blueberries using a spatula.

Pour the batter evenly into the prepared cake pans and bake for 35-40 minutes.

Once baked, let the cakes cool in the pans for 15 minutes before transferring to wire racks to cool completely.

Beat room temperature butter and cream cheese until creamy, then gradually add powdered sugar, lemon juice, and zest until smooth.

Assemble the cake with layers of frosting in between and on the outside, smoothing it out for a polished finish.

Chill the assembled cake for about 30 minutes before decorating with fresh lemon slices and blueberries.