Crush the graham crackers into fine crumbs using a rolling pin inside a plastic bag or a food processor, then transfer to a bowl.
Mix the melted butter into the graham cracker crumbs until evenly coated, then press this mixture firmly into the bottom of a springform pan to form an even crust. Chill in the fridge for 15 minutes to set.
In a large mixing bowl, beat the softened cream cheese with a hand mixer or whisk until smooth and creamy, about 2-3 minutes.
Add the sugar, lemon juice, and vanilla extract to the cream cheese, and beat until fully combined and slightly fluffy.
In a separate bowl, whip the cold heavy cream until soft peaks form, which should take about 3-4 minutes. The cream should shimmer and hold gentle peaks.
Gently fold the whipped cream into the cream cheese mixture using a spatula, folding carefully until smooth and airy, without deflating the mixture.
Pour the filling over the chilled crust, smoothing the top with a spatula for an even surface.
Cover the springform pan with plastic wrap and refrigerate for at least 4 hours, or overnight, until the cheesecake is firm and set.
Once set, run a warm knife around the edge of the cheesecake to loosen it, then carefully remove the sides of the springform pan.
Garnish with fresh berries or lemon zest if desired, then slice with a warm knife for clean cuts and serve chilled.
