Step 1: Make the whipped cream mixture

• In a large mixing bowl, beat the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
• In a separate bowl, fold the mascarpone cheese into the lemon curd until smooth.
• Gently fold the whipped cream into the lemon curd mixture until well combined.

Step 2: Assemble the cake

• Spread a thin layer of the lemon cream mixture on the bottom of an 8×8-inch or 9×13-inch dish.
• Layer graham crackers over the cream, breaking them to fit as needed.
• Spread a generous layer of lemon cream over the graham crackers. Repeat the layers, ending with a layer of lemon cream on top.

Step 3: Chill the cake

• Cover the dish with plastic wrap and refrigerate for at least 4 hours, preferably overnight, to allow the layers to set and the flavors to meld.

Step 4: Garnish and serve

• Before serving, garnish with lemon zest and fresh berries if desired. Slice into squares and serve chilled.