In a chilled large bowl, combine the heavy whipping cream, powdered sugar, and vanilla extract.
Beat on high speed with an electric mixer until stiff peaks form.
Spread a thin layer of whipped cream on the bottom of a 9×9 inch square pan.
Arrange a layer of graham crackers over the cream, breaking them as needed to fit.
Spread one-third of the remaining cream over the crackers, then top with half of the berries.
Repeat with another layer of crackers, one-third of the cream, and the remaining berries.
Finish with a final layer of crackers and the remaining cream.
Cover and refrigerate for at least 6 hours, or overnight, to allow the crackers to soften.