In a small bowl, combine cracker crumbs and sugar; stir in butter. Press onto the bottom of a 9-in. square baking dish coated with cooking spray. Bake at 325° for 7-10 minutes or until set. Cool on a wire rack.
For filling, in a large bowl, beat the cream cheese, sour cream, sugar, flour and vanilla until smooth. Add egg; beat on low just until combined. Remove 3/4 cup batter to a small bowl; stir in pumpkin and brown sugar until well blended.
Pour plain batter over crust. Drop pumpkin batter by tablespoons over plain batter. Cut through batter with a knife to swirl. Bake at 325° for 20-25 minutes or until center is almost set. Cool on a wire rack for 1 hour. Cover and refrigerate for at least 2 hours. Refrigerate leftovers. Yield: 16 servings.