Begin by preparing the crust, which forms the foundation of this no-bake dessert. Place 1 × 9-cracker sleeve of graham crackers into a plastic bag and crush them thoroughly with a rolling pin until you have fine crumbs.
Melt ⅓ cup (75g) of salted butter in a medium saucepan, then remove from heat and stir in the graham cracker crumbs along with 2 tbsps (30g) of demerara sugar until well combined.
Press this mixture evenly over the bottom and sides of a 9-inch springform pan, creating an even layer. Allow the crust to set while you prepare the filling.
For the cheesecake filling, combine 1 × 14-ounce (397g) can of full-fat condensed milk with 1 cup + 2 tbsps (250g) of full-fat mascarpone cheese and the finely grated zest of 3 large lemons in a bowl.
Mix these ingredients together until smooth, then gradually add the juice from the 3 lemons a little at a time while whisking continuously. The mixture will thicken as the lemon juice is incorporated, which indicates the proper emulsification is occurring.
Pour the thickened lemon cheesecake filling onto the prepared graham cracker crust, spreading it evenly across the surface.
Transfer the pan to the refrigerator and allow it to chill for 3–4 hours or overnight, until the filling is completely set and firm. When ready to serve, carefully remove the cheesecake from the springform pan. Top with ⅔ cup (150ml) of freshly whipped heavy cream and arrange fresh strawberries over the surface for an elegant presentation.
