In a large mixing bowl, whisk your crushed graham cracker crumbs with your melted butter. Make sure all the crumbs are moist and there aren't any dry patches.
Pour the crumbs into a 9" spring form pan. Use a rubber spatula or the bottom of a measuring cup to press the crumbs down into an even layer, you should have the crumbs going up slightly at the sides of the pan. Place in the freezer for 20 minutes.
Cheesecake filling
In a stand mixer with the whisk attachment or using a hand held electric mixer, whisk the cold heavy cream for about 5 minutes until you have stiff peaks. Set aside.
In a stand mixer with the paddle attachment, beat the mascarpone on medium speed until completely smooth - you don't want any lumps at all.
Add in your sifted confectioners' sugar, vanilla extract, lemon zest and lemon juice. Beat on medium-high until incorporated and smooth.
Use a rubber spatula to gently fold in your whipped cream, being careful to not deflate the cream.
Pour the filling into your chilled crust. Use a small offset spatula to smooth out the top. Cover in plastic wrap and keep in the fridge overnight. 12 hours is best. Take out of the fridge and remove the sides of the springform pan. Cover the top with fresh berries!
Notes
Heavy Cream: If you're based in the UK, use double cream.Cheesecake Crust: If you don't have graham crackers, feel free to substitute them for an equal weight of digestive biscuits or Biscoff cookies. Storage: Keep your cheesecake in the fridge for up to 5 days. It does not freeze well.