Add boiling water to gelatine; stir 2 min. until completely dissolved. Beat cream cheese in large bowl with mixer until creamy. Gradually add gelatine, beating constantly on low speed until well blended. Add sugar and vanilla; beat 2 min. Gently stir in 1-1/4 cups Cool Whip
. Spoon 1/3 of the cream cheese mixture into plastic wrap-lined 2-L bowl. Arrange jelly rolls in single layer over cream cheese mixture; cover with remaining cream cheese mixture.