HEAT oven to 350ºF.
BEAT first 5 ingredients in large bowl with mixer until blended; stir in carrots and nuts. Pour into 13x9-inch baking dish sprayed with cooking spray.
BAKE 40 to 45 min. or until toothpick inserted in centre comes out clean; cool completely.
BEAT cream cheese and butter in large bowl with mixer until blended. Gradually beat in sugar. Add lemon zest and juice; mix well. Spread onto cake.
serving size = 1 piece (73 g)