Purée strawberries in blender or food processor.
In medium saucepan, combine sugar and gelatin. Stir in milk; stir over low heat until gelatin is completely dissolved, 5-8 minutes.
Pour into large bowl; stir in strawberry purée. Refrigerate, stirring occasionally, until mixture mounds slightly.
Fold whipped cream into thickened gelatin mixture.
Makes about 5 cups mousse.