I made this today for my dad's birthday. It was a big hit with everyone. Even after a heavy meal, several people asked for a second slice. The prep time I've listed of 1 hour and 10 minutes includes 20 minutes freezer time for the crust, and 30 minutes cool time before adding the sour cream topping. Actual prep time of putting together the crust and filling is only about 20 to 25 minutes.
Chill cherry pie filling while preparing tart. Heat oven to 350 degrees.
Combine graham cracker crumbs, 2 Tbs. sugar, and melted butter until all crumbs are moist.
Press into a 9 inch tart pan with removable bottom. Freeze for at least 20 minutes.
In large bowl, beat cream cheese on medium speed until smooth. Beat in 3/4 cup sugar until well mixed and creamy. Add egg and 1/2 tsp. vanilla extract and mix just until combined. Mix in 1/2 cup sour cream on low speed only until evenly mixed. Stir in lemon juice and zest by hand with a rubber spatula (I do this last part by hand to help keep from incorporating too much air into the batter because that can cause the tart to crack).
Place prepared crust on a rimmed baking sheet. Spoon filling into the crust and smooth top. Bake 30 to 35 minutes, just until set. It took 35 minutes in my oven. Remove from oven and allow to cool on the baking sheet for 30 minutes.
While tart is cooling, combine 1 cup sour cream, 1/4 cup sugar and 1 tsp. vanilla extract. After tart has cooled 30 minutes, gently spoon sour cream topping on top, leaving about a 1/4 inch border from edge.
Bake an additional 10 minutes on the baking sheet at 350 degrees. Remove from oven and the baking sheet and allow to cool on a wire rack for 1 hour. Refrigerate for at least 3 hours before removing tart from the pan to a serving platter or cake plate.
Cut into 8 equal slices and serve with chilled pie filling.