Combine OREO cookie crumbs and butter. Press into the base of a 22 cm spring form pan; chill for 20 mins.
Stir the gelatine into the water. Heat in a saucepan (or in microwave on high for 20 seconds) until dissolved.
Beat the PHILADELPHIA cram cheese until soft, stir in all remaining ingredients, including gelatine mixture. Pour into crumb crust and chill until firm for 3 hrs or over night.
Decorate with orange slices.