To make the cracker base: In a bowl, combine graham cracker crumbs, sugar, salt and melted butter. Pour mixture into a greased cooking tray, pressing down firmly using a spatula. Bake at 350°F for 10 minutes or until top is golden brown.
To make chocolate fudge layer: Melt chocolate in a double boiler. Once melted, whisk in condensed milk and vanilla until smooth. Pour fudge over graham cracker base, smoothing out with a spatula so base is completely covered. Place in refrigerator to cool for 10 minutes.
To make the marshmallow layer: Using a spatula, spread marshmallow fluff over the cooled fudge layer. Liberally sprinkle mini marshmallows on top of fluff layer until completely covered. Using a kitchen blowtorch, carefully toast the marshmallows until golden brown; alternatively, broil in the oven a couple of minutes, keeping a close eye so the top doesn’t burn.
Freeze for a few minutes for s’mores to harden, then slice into bars. Serve cool and enjoy!