Preheat your oven to 300°F (150°C) and line a 9-inch springform pan with parchment paper. In a large mixing bowl, blend the full-fat cream cheese until smooth and creamy. Gradually mix in granulated sugar, salt, flour, sour cream, and lemon extract. Add the eggs one at a time, mixing just until combined. Pour the batter into the prepared pan and bake for 45 minutes, until the edges are set but the center is slightly jiggly.

Once baked, turn off the oven and crack the door open, allowing the cheesecake to cool gradually for about 1 hour. Cover the pan and transfer it to the refrigerator, letting it chill for at least 5-6 hours, or ideally overnight.

Preheat your oven to 350°F (175°C) and generously grease and flour two round cake pans. In a mixing bowl, whisk together cake flour, baking powder, and baking soda. In a separate bowl, cream together softened butter and granulated sugar until fluffy. Add eggs and mix well. Combine the dry and wet ingredients alternately with lemon juice and vegetable oil, mixing until just smooth. Divide the batter evenly between the pans and bake for 20-24 minutes, until a toothpick inserted comes out clean.

While the cakes and cheesecake cool, prepare the creamy frosting. In a mixing bowl, beat together softened butter and cream cheese until smooth. Add lemon extract and optional lemon zest for extra zing. Gradually mix in powdered sugar until the frosting reaches a thick yet spreadable consistency.

Begin the assembly by placing the first lemon cake layer on a serving plate. Spread a generous layer of lemon cream cheese frosting on top. Carefully invert the chilled cheesecake layer onto the frosted cake. Frost the top of the cheesecake, then place the second lemon cake layer on top. Cover the entire cake with frosting, smoothing it out beautifully for presentation.

After assembling, chill the complete Creamy Lemon Cheesecake Cake in the refrigerator for at least 30 minutes to set the frosting. Serve with optional fresh berries for garnish.