In a large mixing bowl, beat the cream cheese on low speed for one minute, or until smooth and free of any lumps. Add the eggs, one at a time, and continue to beat slowly just until combined. Do not over-mix! Gradually, add in sugar and beat until creamy. (About 1 minute)
Add sour cream, vanilla and lemon zest. Periodically, scrape down sides of bowl and beaters. The batter should be well-mixed, but not overbeaten. Pour the filling into the crust-filled pan and smooth top with a spatula.
Bake for 45 to 50 minutes. (Be careful not to over-bake!) The center will still be slightly jiggly. Note: It will firm up while it chills. Let cool for 30 minutes, and then loosely cover with Saran Wrap and chill in the refrigerator for at least 4 hours. Carefully loosen the sides of the cheesecake from the pan with a thin spatula or knife, and then carefully remove the sides of the pan.