Begin by pouring cold heavy cream into a large mixing bowl. Using an electric mixer, whip the cream on medium speed for about 2-3 minutes until soft peaks form. Gradually add sugar while continuing to whip for another 2-3 minutes, or until stiff peaks form.

Grab a 13×9-inch baking dish and layer graham crackers at the bottom, ensuring the entire base is covered.

Spread a generous layer of the whipped cream over the graham crackers, covering all completely.

Scatter a layer of mixed berries over the whipped cream, ensuring they are evenly distributed.

Repeat by adding another layer of graham crackers, followed by whipped cream, and then more berries. Finish with a final layer of whipped cream on top.

Cover with plastic wrap and refrigerate for at least 8 hours, preferably overnight.

When ready to serve, slice into portions and enjoy.