HEAT oven to 350°F.
BEAT cream cheese, 3/4 cup butter, granulated sugar and 2 tsp. vanilla in large bowl with mixer until well blended. Mix flour and baking soda; gradually add to cream cheese mixture, mixing well after each addition. Refrigerate 30 min. Press onto bottom of 15x10x1-inch jelly roll pan. Bake 20 min. or until lightly browned.
MELT remaining butter; add to medium bowl. Add brown sugar, corn syrup, eggs and remaining vanilla; beat with whisk until well blended. Stir in nuts. Spread onto crust.
BAKE 20 to 25 min. or until topping is firm around edges but still slightly soft in centre. Cool completely before cutting into bars.