Prepare the sourdough vanilla pound cake according to the recipe instructions and allow it to cool completely. Cut the cake into 1-inch cubes. Wash and prepare the berries. Slice the strawberries and set all of the fruit aside.
In a large mixing bowl, beat the cream cheese until smooth and creamy.
Add the powdered sugar and vanilla extract and beat until fully combined.
Slowly pour in the heavy cream while mixing on low speed. Increase to medium-high speed and beat until stiff peaks form.
Add a layer of pound cake cubes to the bottom of a large trifle dish or glass bowl.
Top with a layer of sliced strawberries and raspberries.
Spread a layer of the cream cheese whipped topping over the berries.
Add another layer of pound cake cubes, followed by a layer of blueberries and blackberries.
Spread another layer of the cream cheese whipped topping over the berries.
Repeat the layers until all ingredients have been used, finishing with whipped topping and fresh berries on top for garnish.
Cover and refrigerate for at least 1 hour before serving to allow the flavors to meld together.