Preheat your oven to 325°F (163°C). Grease and line a 9-inch springform pan with parchment paper for easy removal.
Prepare the cheesecake layer: In a large bowl, beat together the cream cheese and 1/2 cup of the sugar until smooth and creamy. Add 1 egg and half the salt. Mix until fully combined. Gently stir in 1/2 cup sour cream, 2 tablespoons lemon juice, and half the lemon zest.
For the cake layer: In a separate bowl, cream together the butter and remaining 1/2 cup of sugar until light and fluffy. Add the remaining 2 eggs, one at a time, mixing well after each. Stir in the remaining sour cream, lemon juice, and lemon zest.
Whisk together the flour, baking powder, and remaining salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Pour the cake batter into the prepared pan and smooth the surface. Carefully spoon the cheesecake layer over the cake batter and spread evenly.
Bake for 60-70 minutes, or until the top is set and a toothpick inserted into the cake portion comes out mostly clean.
Cool the cake completely in the pan. Chill in the refrigerator for at least 4 hours, or overnight, for best results.
To serve, remove from the springform pan and garnish with extra lemon zest, fresh berries, or a dusting of powdered sugar.
Notes
For best results, use full-fat cream cheese and sour cream. Allow all ingredients to reach room temperature before mixing.