Prepare the Crust: Mix crushed graham crackers, brown sugar, and melted butter until combined. Press half the mixture into the bottom of a 9-inch springform pan, using a dry measuring cup to pack it down firmly. Place in the freezer to set while reserving the other half for the top layer.
Whip the Cream: Whip heavy cream on medium-high for 2 minutes. Add powdered sugar or cornstarch and continue whipping until stiff peaks form (about 4-5 minutes).
Make the Filling: In a separate bowl, beat cream cheese and granulated sugar until smooth. Add sour cream, vanilla extract, lemon juice, and remaining powdered sugar, then beat until fluffy.
Fold in Whipped Cream: Gently fold half of the whipped cream into the cream cheese mixture, then fold in the other half.
Assemble the Cheesecake: Remove the crust from the freezer and pour in the cheesecake filling. Press it down to remove air pockets and smooth the top. Add the remaining graham cracker mixture on top, pressing gently to secure.
Chill: Cover with parchment paper and refrigerate for at least 8 hours, or overnight, to set.
Serve: Slice and serve plain, or top with fresh strawberries or whipped cream.
