Soften gelatin in 1/2 cup cold water. Bring remaining 3/4 cup water to boil in small saucepan. Add gelatin, then sugar and stir until dissolved. Set aside to cool. Turn cooled mixture into blender container. Add mango and puree. Add milk, ice cream and vanilla. Blend 2 minutes, stopping and starting at 30-second intervals. Turn into 2-quart bowl. Cover and chill 4 hours or longer. To serve, spoon pudding into dessert bowls or glasses. Garnish with mango slices. Note: If using canned mango, reduce sugar to 3/4 cup Drain well so as not to increase liquid content.