In a large bowl, stir together berries, ¼ cup brown sugar, corn starch and lemon juice. Layer into a lightly greased 9-inch pie dish or 4 to 6 lightly-greased ramekins.
In another bowl, stir together oats, ¼ cup brown sugar, butter and cinnamon. Sprinkle over the top of the fruit layer.
Line a baking sheet with aluminum foil and place under pie dish or ramekins. Bake for 30-40 minutes, until berries bubble and oats are crispy. Cool for 30 minutes before serving.
Then make the whipped cream. Combine all ingredients in a medium bowl. Use an electric mixer to whip the cream until stiff peaks form. Refrigerate until ready to serve.