magic s’mores bars

10 ounces (300g) graham crackers (18 whole crackers, or two cellophane wrapped stacks)
1 1/2 sticks (12 tablespoons) unsalted butter, melted
1 pinch of kosher salt
1 14 ounce can (400g) sweetened condensed milk
1 1/2 cups (250g) semisweet chocolate chips
2 cups (I have no idea how much they weigh—just throw a couple of handfuls on!) mini marshmallows

1. Preheat the oven to 350 degrees (180 degrees Celsius). In a large resealable bag (or in a food processor), smash graham crackers until finely ground. Stir in melted butter and salt. Press into a 13×9″ pan.  Bake for 5 minutes.  Remove from oven.
2. Sprinkle on chocolate chips. Drizzle can of condensed milk over graham crackers; follow with marshmallows.
3. Bake for 20 minutes more, until marshmallows are lightly browned.  Let cool completely.