Place a bowl for stand mixer and wire whip mixer attachment in the freezer for about 10 minutes. Meanwhile cut angel food cake into 1 inch cubes. Place half of them in the bottom of a glass trifle dish.
Remove bowl and attachment from freezer. Add heavy cream and sugar to mixing bowl and mix on medium high speed for several minutes until stiff peaks form. Spoon half into bowl over angel food cubes. Arrange half of strawberries and half of blueberries over whipped cream.
Add another layer of angel food cake cubes followed by the remaining whipped cream. Arrange remaining blueberries and strawberries on top. Garnish with mint if desired.
Serve immediately or refrigerate for several hours until serving.