Line a 9 x 9-inch (23 x 23 cm) baking pan with parchment paper, leaving enough overhang on all sides to help lift the cake out later.
Add the granulated sugar and lemon zest to a small bowl. Rub the zest into the sugar with your fingertips for about 1 minute until fragrant.
½ cup (100 g) granulated sugar, 2 tsps (12 g) lemon zest
Add the cold heavy cream, vanilla bean paste, mascarpone cheese, and lemon sugar mixture to the bowl of a stand mixer fitted with the whisk attachment. Beat on low speed until the mascarpone loosens and the mixture begins to thicken. Increase the speed to medium-high and continue beating until thick, creamy, and able to hold soft peaks.
1 pint (2 cups / 16 oz / 473 ml) heavy whipping cream, 1 tbsp (15 ml) vanilla bean paste, 16 oz (454 g) mascarpone cheese
Spread a very thin layer of mascarpone cream onto the bottom of the prepared pan. Arrange a single layer of graham crackers over the cream, breaking pieces as needed to cover the bottom of the pan without overlapping.
1 box (14.4 oz / 408 g) graham crackers
Spread one-fourth of the mascarpone cream evenly over the graham crackers. Spoon ½ cup (130 g) lemon curd over the cream and gently spread into an even layer. Top with another layer of graham crackers.
1 cup (260 g) lemon curd
Spread another one-fourth of the mascarpone cream over the graham crackers. Arrange a layer of thinly sliced strawberries evenly over the cream. Top with another layer of graham crackers.
16 oz (454 g) fresh strawberries
Spread another one-fourth of the mascarpone cream over the graham crackers. Add the remaining ½ cup (130 g) lemon curd and spread into an even layer. Top with another layer of graham crackers.
Spread the remaining mascarpone cream evenly over the top. Cover the pan with parchment paper or plastic wrap and refrigerate overnight, or for at least 8 hours, until the graham crackers soften into cake-like layers.
Use the parchment overhang to lift the chilled cake out of the pan and transfer it to a serving platter. Top with extra sliced strawberries and lemon zest before slicing.
Slice into 9 pieces and serve cold.