1.HEAT oven to 350°F. Lightly spray 13x9-inch baking pan with no-stick cooking spray. Knead package of streusel to break up chunks. Place 1/3 cup streusel in small bowl. Stir in walnuts. Set aside. 2.STIR together mix and remaining streusel in large bowl. Stir in butter, 2 eggs, water and pumpkin until blended. Spread batter into prepared pan. 3.BEAT cream cheese and sour cream in medium bowl with electric mixer at medium high speed until smooth. Beat in sugar, flour, 1 egg and vanilla until blended. Pour over batter in pan. Swirl topping into batter in a few wide loops with a kitchen knife to form some pockets of cream cheese in filling. Sprinkle with streusel and nuts. 4.BAKE 35 to 40 minutes or until center is set and edges are light golden brown. Serve warm or at room temperature. Store in refrigerator.