Creamy JELL-O Mosaic Dessert

Add 1 cup boiling water to each flavor of fruit gelatin mix in separate bowls; stir 2 min. until completely dissolved. Pour each flavor of gelatin into separate 8x4-inch loaf pan sprayed with cooking spray. Refrigerate 2 hours or until firm.

Meanwhile, stir unflavored gelatine into 1-1/2 cups milk; let stand 5 min. or until gelatine is softened. Bring 2 cups of the remaining milk just to boil in large saucepan on medium heat. Add sugar and unflavored gelatin mixture; cook and stir 3 to 5 min. or until sugar is dissolved. Remove from heat; cool 5 min. Add sour cream, vanilla and remaining milk; whisk until blended. Refrigerate 30 min. or until cooled but not firm.

Cut flavored gelatin into 1/2-inch cubes; place in 12-cup mold sprayed with cooking spray. Pour milk mixture over gelatin cubes. Refrigerate 2 hours or until gelatin is firm. Unmold before serving.