• Place a 10-inch cake card on the counter.
• Remove the bottom from a 9-inch spring form pan. Put the pan on top of the cake card. Line the inside of the pan with an acetate cake collar.
• Put the graham crackers in a large ziploc bag and bash with a rolling pin until fine crumbs form. Pour the melted butter into the ziploc, and mash around with the cookie crumbs to fully combine.
• Put the buttery graham cracker crumbs in the bottom of the pan and press to form a flat surface. Store the base in the refrigerator while you make the mousse.
• Prepare the strawberry base by pulsing the strawberries in a food processor until fully pureed. Run the puree through a fine-meshed sieve into a large bowl. Set aside 1/4 of the strawberry base in a separate bowl for the strawberry topping. The remaining 3/4 will be used for the strawberry mousse.

Make the strawberry mousse

• Sprinkle the gelatine over the water and let sit for 30 seconds to bloom while you stir the lemon juice into the larger portion of the strawberry puree. Pour 1/4 cup of the the strawberry puree and bloomed gelatin into a small saucepan and stir over low heat until the gelatine is fully dissolved. Combine the strawberry-gelatine mixture with the remaining strawberry puree. Let cool while you beat the whipping cream.
• In the bowl of a stand mixer using the whisk attachment, or in a large bowl using an electric mixer, whip cream, mascarpone cheese, powdered sugar, and salt on low speed until whipped and fluffy, about 5 minutes.
• Pour the cooled strawberry mixture into the whipped cream mixture. Use a rubber spatula to fold the strawberry mixture into the whipped cream until no more streaks remain.
• Pour the strawberry mousse in an even layer into the prepared crust. Use an offset spatula to cover the top. Cover the cake with plastic wrap. Refrigerate 2 hours until set.

Make the strawberry gelatin topping

• Sprinkle the gelatine over the water and let sit for 30 seconds. Combine the gelatine, remaining strawberry puree, and sugar, in a small saucepan. Stir over low heat until all of the gelatine is melted. Let cool for 15 minutes.
• Pour the strawberry topping over the mousse to evenly cover the mousse surface. Let cool until set, at least six hours or overnight.
• Just before serving, pipe whipped cream and sprinkle fresh berries and mint leaves over the top.