Pulse graham crackers in a food processor until fine. Mix with melted butter. Press evenly into the bottom of a parchment-lined 9×9-inch baking pan. Chill while preparing filling.

Beat cream cheese and brown sugar until smooth. Add flour, spices, vanilla (if using), and pumpkin; mix until combined. Add one egg, mix well, then add the remaining eggs one at a time. Stir in heavy cream until smooth.

Oven: Pour filling over crust. Bake at 350°F for 55–60 minutes, until center is just set. Cool to room temperature, then chill at least 4 hours.

Instant Pot (7-inch round only): Follow original recipe with springform pan and pressure cook for 28 minutes.

Top cooled cheesecake with mini marshmallows, chopped chocolate, and crushed graham crackers. Torch marshmallows until golden.

Once chilled and firm, use a sharp knife to cut into 12 equal bars. Wipe blade clean between cuts for sharp edges. Serve cold or at room temperature.