Lightly whip the cream
Add the heavy cream to a bowl and beat with a whisk until the mixture is lighter and slightly fluffy, about 3 minutes.
Add grand marnier
Add the Grand Marnier and fold it in with a rubber spatula (optional - omit for non-alcoholic). Cover and refrigerate until ready to use.
Divide the sliced berries among small bowls and top with the whipped cream followed by a sprinkle of sugar. Serve immediately.