1. Preheat oven to 350 degrees. Butter the bottom and sides of a 9-inch springform pan. In a food processor, place graham crackers and brown sugar; process until finely ground. Add butter; process until moist crumbs form. Press mixture into bottom and 2 inches up sides of pan; set aside.

2. In a large mixing bowl, beat cream cheese, 1 1/2 cups granulated sugar, salt, and 1 teaspoon vanilla until smooth. Add eggs one at a time, beating after each addition and scraping down sides of bowl. Pour filling into pan; bake until light brown and center is almost set, about 50 minutes. Let cool 15 minutes.

3. Meanwhile, raise heat to 450 degrees. In a bowl, combine sour cream, remaining 1/4 cup granulated sugar, and 1 1/2 teaspoons vanilla. After cake has cooled 15 minutes, spread topping with a spatula, leaving a 1/2-inch border. Bake 10 minutes.

4. Let cool, then refrigerate in pan at least 12 hours. Run a knife around edge of pan before releasing sides.