Step 1: Slice the pound cake into 1-inch thick slices, then cut each slice into 1-inch cubes. Set aside.
Step 2: Gently rinse the strawberries and blueberries. Hull and slice the strawberries. Pat all berries thoroughly dry with paper towels.
Step 3: In a very cold mixing bowl, combine the heavy cream, powdered sugar, and vanilla extract. Beat with an electric mixer on medium-high speed until stiff peaks form.
Step 4: In a large trifle dish (about 3-quart capacity), arrange a single layer of pound cake cubes to cover the bottom.
Step 5: Spread about half of the sliced strawberries evenly over the pound cake layer.
Step 6: Spoon about one-third of the whipped cream over the strawberries, gently spreading it to the edges.
Step 7: Add another layer of pound cake cubes on top of the whipped cream.
Step 8: Evenly spread about half of the blueberries over the second pound cake layer.
Step 9: Spoon another one-third of the whipped cream over the blueberries, spreading it gently.
Step 10: Add the remaining pound cake cubes, followed by the remaining sliced strawberries.
Step 11: Scatter the remaining blueberries over the strawberries. Top with the remaining whipped cream, creating a beautiful domed top. You can use a spatula to create swirls or a piping bag for a more decorative finish.
Step 12: Cover the trifle lightly with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the flavors to meld and the cake to soften.