Combine flour and baking soda. Beat cream cheese and 3/4 cup butter in large bowl with mixer until blended. Add granulated sugar and 2 tsp. vanilla; mix well. Gradually add flour mixture, mixing well after each addition. Refrigerate 30 min.
Heat oven to 350°F. Press dough onto bottom of 15x10x1-inch pan.
Bake 20 min. or until lightly browned. Meanwhile, melt remaining butter; pour into medium bowl. Add eggs, brown sugar, corn syrup and remaining vanilla; mix well. Stir in nuts.
Spread nut mixture over warm crust. Bake 20 to 25 min. or until topping is firm around the edges but still slightly soft in the center. Cool completely.