Heat the oven to 350°F. Lightly grease a 9 × 13-inch glass baking dish, or line it with parchment paper.
Arrange six whole graham cracker sheets in a single layer across the bottom of the prepared baking dish.
Crush the remaining graham crackers into fine crumbs. Combine the crumbs with the melted butter, mixing until evenly coated.
Sprinkle half of the chocolate chips evenly over the graham cracker layer.
Spread half of the buttered graham cracker crumbs over the chocolate chips.
Add another layer of graham crackers, followed by the remaining chocolate chips and graham cracker crumbs.
Slowly drizzle the sweetened condensed milk over the entire surface, making sure it reaches as much of the dessert as possible.
Place the dish in the preheated oven and bake for 25–30 minutes, or until the top is lightly golden and the edges are bubbling.
Remove from the oven and allow the dessert to cool completely before slicing into squares or bars.
