Mix together oats, 1/2 cup brown sugar, butter and flour. Refrigerate. Mix fruit together with lemon juice, 1/2 cup of light brown sugar and cornstarch. Place in baking dish.
Preheat oven to 375 degrees. Place crumble on top of fruit mixture and bake for 40 minutes.
For whipped cream, place cream in a stand mixer and beat until soft peaks form. Add remaining ingredients and chill until ready to serve.