Prepare the crust: Preheat oven to 325°F (163°C). Mix graham cracker crumbs, melted butter, and sugar until well combined. Press firmly into the bottom of a 9-inch springform pan. Bake for 10 minutes, then cool completely.

Make the filling: Beat cream cheese on medium speed for 2 minutes until fluffy. Gradually add sugar, then mix in sour cream, vanilla, and salt until smooth. Add eggs one at a time on low speed, mixing just until incorporated.

Fold in mix-ins: Gently fold mini marshmallows and chocolate chips into the batter by hand. Pour filling over cooled crust and tap pan on counter three times to release air bubbles.

Bake the cheesecake: Bake at 325°F for 60-70 minutes until edges are set but center still jiggles slightly (internal temperature should reach 145°F). Turn off oven and let cheesecake sit inside with door closed for 1 hour.

Cool gradually: Crack oven door and let cheesecake sit for 30 more minutes. Remove from oven and cool completely at room temperature, then refrigerate overnight or at least 8 hours.

Prepare ganache: Heat heavy cream until small bubbles form around edges. Pour over chocolate chips in a bowl, let sit 2 minutes, then whisk from center outward until smooth and glossy. Pour over chilled cheesecake and refrigerate 30 minutes to set.

Toast marshmallows: Arrange jumbo marshmallows on top of ganache. Use a kitchen torch to toast marshmallows until golden with caramelized patches, or broil for 30-60 seconds watching carefully. Drizzle with extra ganache if desired.

Serve: Let cheesecake sit at room temperature for 15 minutes before slicing. Wipe knife clean between cuts for neat slices. Store covered in refrigerator for up to 5 days.