Pour the heavy cream into a large bowl. Use a hand mixer or whisk to beat it until soft peaks form, about 2-3 minutes. Add powdered sugar and vanilla extract, then continue beating until the cream thickens and forms stiff peaks. Set aside.

Spread a thin layer of whipped cream on the bottom of the 9x9 baking pan. This will help the graham crackers stay in place.

Place a single layer of graham crackers on the whipped cream. Break the crackers as needed to fit the pan, covering the surface completely.

Spread a layer of whipped cream over the graham crackers, using about 1/3 of the whipped cream. Arrange a layer of strawberry slices evenly on top of the cream.

Repeat this layering process (graham crackers, whipped cream, strawberries) two more times, ending with a final layer of whipped cream on top. Save a few strawberry slices for decoration, if desired.

Cover the baking pan with plastic wrap and refrigerate for at least 6 hours or overnight. This will allow the graham crackers to soften and absorb the flavors.

Before serving, add the reserved strawberries on top as decoration. Slice and serve chilled. Enjoy!