In a large mixing bowl, beat the heavy whipping cream, powdered sugar, and vanilla extract until soft peaks form.
In another bowl, mix the softened cream cheese and sour cream until smooth and well combined.
Gently fold the whipped cream into the cream cheese mixture until fully incorporated.
On a serving platter, arrange a layer of graham crackers to cover the bottom.
Spread a layer of the cream mixture over the crackers, then add a layer of sliced strawberries and blueberries.
Repeat the layers, finishing with a layer of the cream mixture on top.
Decorate the top with remaining berries.
Cover the cake with plastic wrap and refrigerate for at least 4 hours, or overnight for best results.