In a medium saucepan, combine sugar and unflavored gelatin. Stir in evaporated milk. Cook and stir until sugar and gelatin dissolve. Remove from heat.

Place rhubarb and raspberries in a large bowl. Place blackberries in another large bowl. Divide hot sugar mixture between the two bowls of fruit. Let stand for 5 minutes. Using potato masher, mash fruit in each bowl. Spoon half of the sour cream into fruit in each bowl; stir until well mixed. Pour fruit mixtures into two separate 2-quart square baking dishes or 2-quart shallow freezer containers. Cover and freeze about 5 hours or until mixtures are firm but not totally frozen, stirring occasionally so mixtures freeze evenly.

Meanwhile, in the same medium saucepan, heat white chocolate over low heat until melted and smooth, stirring frequently. Gradually add cream cheese, stirring until well mixed. Gradually stir in milk until smooth. Pour mixture into another 2-quart square baking dish or 2-quart shallow freezer container. Cover and freeze for 3 to 4 hours or until firm but not totally frozen, stirring occasionally so mixture freezes evenly.

For each frozen mixture, break up mixture and transfer to a large food processor or large chilled bowl. Cover and process until smooth but not melted. Or if using the large bowl, beat with an electric mixer on medium speed until smooth and fluffy but not melted. Spread mixtures back into the 2-quart baking dishes or freezer containers, keeping mixtures separate. Cover and freeze for 2 to 3 hours or until mixtures are frozen. Let stand at room temperature for 20 minutes before serving. Using a tiny scoop, place a scoop of each frozen mixture into dessert dishes.

We do not recommend sugar substitutes for this recipe.

If using frozen rhubarb, measure while frozen. Thaw; do not drain.