Make the crust: In a bowl, stir graham cracker crumbs, melted butter, sugar (if using), and a pinch of salt until the mixture looks like wet sand and holds together when pressed.
Pack the base: Spoon 2–3 tablespoons of crust mixture into each jar. Press down firmly with the back of a spoon or a small glass. Set aside.
Beat the cream cheese: In a large bowl, beat softened cream cheese until smooth and fluffy, about 1–2 minutes. Scrape the bowl.
Sweeten and flavor: Add powdered sugar, vanilla, lemon juice, and zest. Beat until well combined and silky. Taste and adjust sweetness or lemon to your liking.
Whip the cream: In a separate bowl, whip cold heavy cream with a pinch of salt to stiff peaks. Don’t overwhip.
Fold gently: Add one-third of the whipped cream to the cream cheese mixture and fold to lighten. Fold in the remaining whipped cream until no streaks remain.
Fill the jars: Pipe or spoon the cheesecake filling over the crusts, leaving space for toppings. Smooth the tops.
Chill: Cover and refrigerate for at least 3 hours, or up to overnight, until set and spoonable.
Add toppings: Just before serving, add berries, compote, sauce, or your favorite toppings. Serve cold.