Preheat oven to 300°F (149°C). Beat 16 oz of cream cheese until smooth, then add 1 cup sugar, 3 tbsp flour, salt, and 1 cup sour cream, mixing well. Add 1 tsp lemon extract and 3 eggs one at a time. Pour into a springform pan in a water bath and bake for 45 minutes. Cool and refrigerate.

Increase oven to 350°F (175°C). Grease and flour two 9-inch cake pans. Whisk together 2 cups flour, 1 tsp baking powder, 0.5 tsp baking soda, 0.5 tsp salt, and zest of 1 lemon. Mix 1 cup buttermilk, 0.5 cup vegetable oil, 1 tsp lemon extract, and 0.25 cup lemon juice. Cream 0.5 cup butter with 1 cup sugar until fluffy, add 2 eggs, then alternate flour and buttermilk mixtures. Pour into pans and bake for 20-24 min until a toothpick comes out clean.

Beat together 8 oz of softened butter and 8 oz of cream cheese until creamy. Mix 1 tsp lemon extract and zest if desired. Gradually add 4 cups powdered sugar, beating until light and spreadable.

Place the first lemon cake layer on a serving plate, spread frosting, add the cheesecake, another layer of frosting, and finally the second lemon cake layer. Frost the exterior and chill for at least 30 minutes before serving.