Crush graham crackers with rolling pin until smooth. Mix crumbs with butter and 3/4 cup sugar and press into bottom of 9-inch square pan or disposable aluminum pan.
Add cream cheese filling to crust and cook in 350° oven for 45 minutes. Turn oven off and let cake cook for 20–30 minutes, or until golden brown. Take cake out of oven and let cool.
Mix sour cream, vanilla and 1/2 cup sugar together. Pour topping over cake and put in 450° oven for 8–10 minutes. Take out and let cool. Refrigerate.