• Set a rack on the lowest level of the oven and preheat to 325 degrees F.
• Beat 16 ounces softened cream cheese and ½ cup sugar in the bowl of an electric mixer set on low speed. Beat for one minute, or until the mixture is smooth. Stop the mixer and scrape down the bowl.
• Add 1 teaspoon vanilla, 2 teaspoons lemon zest, and one of the eggs. Beat on low speed until smooth. Scrape down again and add the second egg. Beat and scrape again. Follow the same procedure for adding the egg yolks, one at a time. Beat in the sour cream until smooth.
• Use a large rubber spatula to give a final mixing to the filling and scrape it into the prepared pastry crust, smoothing the top.
• Bake the tart until the crust is baked through and the filling is set and no longer wobbly in the center, about 30 minutes.

While the Tart is Baking, Prepare the GLaze:

• Whisk together 1 cup sour cream, 3 Tablespoons sugar, and 1 teaspoon vanilla until just combined. Remove the tart from the oven and immediately scrape the sour-cream mixture over the top. use a small offset metal spatula to spread the glaze evenly all over the tart.
• Return the tart to the oven and bake 10 minutes longer, just to set the glaze - it will firm as it cools. Cool the tart on a rack.

Storing the Tart:

• This tart tastes best on the day it is made. Keep the tart at a cool room temperature on the day it is baked. Wrap loosely in plastic and refrigerate leftovers. Bring to room temperature before serving again.